Some dialogues of Plato are of so various a character that their relation to the other dialogues cannot be determined with any degree of certainty. The Theaetetus, like the Parmenides, has points of similarity both with his earlier and his later writings. The perfection of style, the humour, the dramatic interest, the complexity of structure, the fertility of illustration, the shifting of the points of view, are characteristic of his best period of authorship. The vain search, the negative conclusion, the figure of the midwives, the constant profession of ignorance on the part of Socrates, also bear the stamp of the early dialogues, in which the original Socrates is not yet Platonized. Had we no other indications, we should be disposed to range the Theaetetus with the Apology and the Phaedrus, and perhaps even with the Protagoras and the Laches.

But when we pass from the style to an examination of the subject, we trace a connection with the later rather than with the earlier dialogues. In the first place there is the connexion, indicated by Plato himself at the end of the dialogue, with the Sophist, to which in many respects the Theaetetus is so little akin. (1) The same persons reappear, including the younger Socrates, whose name is just mentioned in the Theaetetus; (2) the theory of rest, which Socrates has declined to consider, is resumed by the Eleatic Stranger; (3) there is a similar allusion in both dialogues to the meeting of Parmenides and Socrates (Theaet., Soph.); and (4) the inquiry into not-being in the Sophist supplements the question of false opinion which is raised in the Theaetetus. (Compare also Theaet. and Soph. for parallel turns of thought.) Secondly, the later date of the dialogue is confirmed by the absence of the doctrine of recollection and of any doctrine of ideas except that which derives them from generalization and from reflection of the mind upon itself. The general character of the Theaetetus is dialectical, and there are traces of the same Megarian influences which appear in the Parmenides, and which later writers, in their matter of fact way, have explained by the residence of Plato at Megara. Socrates disclaims the character of a professional eristic, and also, with a sort of ironical admiration, expresses his inability to attain the Megarian precision in the use of terms. Yet he too employs a similar sophistical skill in overturning every conceivable theory of knowledge.

The direct indications of a date amount to no more than this: the conversation is said to have taken place when Theaetetus was a youth, and shortly before the death of Socrates. At the time of his own death he is supposed to be a full-grown man. Allowing nine or ten years for the interval between youth and manhood, the dialogue could not have been written earlier than 390, when Plato was about thirty-nine years of age. No more definite date is indicated by the engagement in which Theaetetus is said to have fallen or to have been wounded, and which may have taken place any time during the Corinthian war, between the years 390-387. The later date which has been suggested, 369, when the Athenians and Lacedaemonians disputed the Isthmus with Epaminondas, would make the age of Theaetetus at his death forty-five or forty-six. This a little impairs the beauty of Socrates' remark, that 'he would be a great man if he lived.'

In this uncertainty about the place of the Theaetetus, it seemed better, as in the case of the Republic, Timaeus, Critias, to retain the order in which Plato himself has arranged this and the two companion dialogues. We cannot exclude the possibility which has been already noticed in reference to other works of Plato, that the Theaetetus may not have been all written continuously; or the probability that the Sophist and Politicus, which differ greatly in style, were only appended after a long interval of time. The allusion to Parmenides compared with the Sophist, would probably imply that the dialogue which is called by his name was already in existence; unless, indeed, we suppose the passage in which the allusion occurs to have been inserted afterwards. Again, the Theaetetus may be connected with the Gorgias, either dialogue from different points of view containing an analysis of the real and apparent (Schleiermacher); and both may be brought into relation with the Apology as illustrating the personal life of Socrates. The Philebus, too, may with equal reason be placed either after or before what, in the language of Thrasyllus, may be called the Second Platonic Trilogy. Both the Parmenides and the Sophist, and still more the Theaetetus, have points of affinity with the Cratylus, in which the principles of rest and motion are again contrasted, and the Sophistical or Protagorean theory of language is opposed to that which is attributed to the disciple of Heracleitus, not to speak of lesser resemblances in thought and language. The Parmenides, again, has been thought by some to hold an intermediate position between the Theaetetus and the Sophist; upon this view, the Sophist may be regarded as the answer to the problems about One and Being which have been raised in the Parmenides. Any of these arrangements may suggest new views to the student of Plato; none of them can lay claim to an exclusive probability in its favour.

The Theaetetus is one of the narrated dialogues of Plato, and is the only one which is supposed to have been written down. In a short introductory scene, Euclides and Terpsion are described as meeting before the door of Euclides' house in Megara. This may have been a spot familiar to Plato (for Megara was within a walk of Athens), but no importance can be attached to the accidental introduction of the founder of the Megarian philosophy. The real intention of the preface is to create an interest about the person of Theaetetus, who has just been carried up from the army at Corinth in a dying state. The expectation of his death recalls the promise of his youth, and especially the famous conversation which Socrates had with him when he was quite young, a few days before his own trial and death, as we are once more reminded at the end of the dialogue. Yet we may observe that Plato has himself forgotten this, when he represents Euclides as from time to time coming to Athens and correcting the copy from Socrates' own mouth. The narrative, having introduced Theaetetus, and having guaranteed the authenticity of the dialogue (compare Symposium, Phaedo, Parmenides), is then dropped. No further use is made of the device. As Plato himself remarks, who in this as in some other minute points is imitated by Cicero (De Amicitia), the interlocutory words are omitted.

Theaetetus, the hero of the battle of Corinth and of the dialogue, is a disciple of Theodorus, the great geometrician, whose science is thus indicated to be the propaedeutic to philosophy. An interest has been already excited about him by his approaching death, and now he is introduced to us anew by the praises of his master Theodorus. He is a youthful Socrates, and exhibits the same contrast of the fair soul and the ungainly face and frame, the Silenus mask and the god within, which are described in the Symposium. The picture which Theodorus gives of his courage and patience and intelligence and modesty is verified in the course of the dialogue. His courage is shown by his behaviour in the battle, and his other qualities shine forth as the argument proceeds. Socrates takes an evident delight in 'the wise Theaetetus,' who has more in him than 'many bearded men'; he is quite inspired by his answers. At first the youth is lost in wonder, and is almost too modest to speak, but, encouraged by Socrates, he rises to the occasion, and grows full of interest and enthusiasm about the great question. Like a youth, he has not finally made up his mind, and is very ready to follow the lead of Socrates, and to enter into each successive phase of the discussion which turns up. His great dialectical talent is shown in his power of drawing distinctions, and of foreseeing the consequences of his own answers. The enquiry about the nature of knowledge is not new to him; long ago he has felt the 'pang of philosophy,' and has experienced the youthful intoxication which is depicted in the Philebus. But he has hitherto been unable to make the transition from mathematics to metaphysics. He can form a general conception of square and oblong numbers, but he is unable to attain a similar expression of knowledge in the abstract. Yet at length he begins to recognize that there are universal conceptions of being, likeness, sameness, number, which the mind contemplates in herself, and with the help of Socrates is conducted from a theory of sense to a theory of ideas.

There is no reason to doubt that Theaetetus was a real person, whose name survived in the next generation. But neither can any importance be attached to the notices of him in Suidas and Proclus, which are probably based on the mention of him in Plato. According to a confused statement in Suidas, who mentions him twice over, first, as a pupil of Socrates, and then of Plato, he is said to have written the first work on the Five Solids. But no early authority cites the work, the invention of which may have been easily suggested by the division of roots, which Plato attributes to him, and the allusion to the backward state of solid geometry in the Republic. At any rate, there is no occasion to recall him to life again after the battle of Corinth, in order that we may allow time for the completion of such a work (Muller). We may also remark that such a supposition entirely destroys the pathetic interest of the introduction.

Theodorus, the geometrician, had once been the friend and disciple of Protagoras, but he is very reluctant to leave his retirement and defend his old master. He is too old to learn Socrates' game of question and answer, and prefers the digressions to the main argument, because he finds them easier to follow. The mathematician, as Socrates says in the Republic, is not capable of giving a reason in the same manner as the dialectician, and Theodorus could not therefore have been appropriately introduced as the chief respondent. But he may be fairly appealed to, when the honour of his master is at stake. He is the 'guardian of his orphans,' although this is a responsibility which he wishes to throw upon Callias, the friend and patron of all Sophists, declaring that he himself had early 'run away' from philosophy, and was absorbed in mathematics. His extreme dislike to the Heraclitean fanatics, which may be compared with the dislike of Theaetetus to the materialists, and his ready acceptance of the noble words of Socrates, are noticeable traits of character.

The Socrates of the Theaetetus is the same as the Socrates of the earlier dialogues. He is the invincible disputant, now advanced in years, of the Protagoras and Symposium; he is still pursuing his divine mission, his 'Herculean labours,' of which he has described the origin in the Apology; and he still hears the voice of his oracle, bidding him receive or not receive the truant souls. There he is supposed to have a mission to convict men of self-conceit; in the Theaetetus he has assigned to him by God the functions of a man-midwife, who delivers men of their thoughts, and under this character he is present throughout the dialogue. He is the true prophet who has an insight into the natures of men, and can divine their future; and he knows that sympathy is the secret power which unlocks their thoughts. The hit at Aristides, the son of Lysimachus, who was specially committed to his charge in the Laches, may be remarked by the way. The attempt to discover the definition of knowledge is in accordance with the character of Socrates as he is described in the Memorabilia, asking What is justice? what is temperance? and the like. But there is no reason to suppose that he would have analyzed the nature of perception, or traced the connexion of Protagoras and Heracleitus, or have raised the difficulty respecting false opinion. The humorous illustrations, as well as the serious thoughts, run through the dialogue. The snubnosedness of Theaetetus, a characteristic which he shares with Socrates, and the man-midwifery of Socrates, are not forgotten in the closing words. At the end of the dialogue, as in the Euthyphro, he is expecting to meet Meletus at the porch of the king Archon; but with the same indifference to the result which is everywhere displayed by him, he proposes that they shall reassemble on the following day at the same spot. The day comes, and in the Sophist the three friends again meet, but no further allusion is made to the trial, and the principal share in the argument is assigned, not to Socrates, but to an Eleatic stranger; the youthful Theaetetus also plays a different and less independent part. And there is no allusion in the Introduction to the second and third dialogues, which are afterwards appended. There seems, therefore, reason to think that there is a real change, both in the characters and in the design.

The dialogue is an enquiry into the nature of knowledge, which is interrupted by two digressions. The first is the digression about the midwives, which is also a leading thought or continuous image, like the wave in the Republic, appearing and reappearing at intervals. Again and again we are reminded that the successive conceptions of knowledge are extracted from Theaetetus, who in his turn truly declares that Socrates has got a great deal more out of him than ever was in him. Socrates is never weary of working out the image in humorous details,—discerning the symptoms of labour, carrying the child round the hearth, fearing that Theaetetus will bite him, comparing his conceptions to wind-eggs, asserting an hereditary right to the occupation. There is also a serious side to the image, which is an apt similitude of the Socratic theory of education (compare Republic, Sophist), and accords with the ironical spirit in which the wisest of men delights to speak of himself.

The other digression is the famous contrast of the lawyer and philosopher. This is a sort of landing-place or break in the middle of the dialogue. At the commencement of a great discussion, the reflection naturally arises, How happy are they who, like the philosopher, have time for such discussions (compare Republic)! There is no reason for the introduction of such a digression; nor is a reason always needed, any more than for the introduction of an episode in a poem, or of a topic in conversation. That which is given by Socrates is quite sufficient, viz. that the philosopher may talk and write as he pleases. But though not very closely connected, neither is the digression out of keeping with the rest of the dialogue. The philosopher naturally desires to pour forth the thoughts which are always present to him, and to discourse of the higher life. The idea of knowledge, although hard to be defined, is realised in the life of philosophy. And the contrast is the favourite antithesis between the world, in the various characters of sophist, lawyer, statesman, speaker, and the philosopher,—between opinion and knowledge,—between the conventional and the true.

The greater part of the dialogue is devoted to setting up and throwing down definitions of science and knowledge. Proceeding from the lower to the higher by three stages, in which perception, opinion, reasoning are successively examined, we first get rid of the confusion of the idea of knowledge and specific kinds of knowledge,—a confusion which has been already noticed in the Lysis, Laches, Meno, and other dialogues. In the infancy of logic, a form of thought has to be invented before the content can be filled up. We cannot define knowledge until the nature of definition has been ascertained. Having succeeded in making his meaning plain, Socrates proceeds to analyze (1) the first definition which Theaetetus proposes: 'Knowledge is sensible perception.' This is speedily identified with the Protagorean saying, 'Man is the measure of all things;' and of this again the foundation is discovered in the perpetual flux of Heracleitus. The relativeness of sensation is then developed at length, and for a moment the definition appears to be accepted. But soon the Protagorean thesis is pronounced to be suicidal; for the adversaries of Protagoras are as good a measure as he is, and they deny his doctrine. He is then supposed to reply that the perception may be true at any given instant. But the reply is in the end shown to be inconsistent with the Heraclitean foundation, on which the doctrine has been affirmed to rest. For if the Heraclitean flux is extended to every sort of change in every instant of time, how can any thought or word be detained even for an instant? Sensible perception, like everything else, is tumbling to pieces. Nor can Protagoras himself maintain that one man is as good as another in his knowledge of the future; and 'the expedient,' if not 'the just and true,' belongs to the sphere of the future.

And so we must ask again, What is knowledge? The comparison of sensations with one another implies a principle which is above sensation, and which resides in the mind itself. We are thus led to look for knowledge in a higher sphere, and accordingly Theaetetus, when again interrogated, replies (2) that 'knowledge is true opinion.' But how is false opinion possible? The Megarian or Eristic spirit within us revives the question, which has been already asked and indirectly answered in the Meno: 'How can a man be ignorant of that which he knows?' No answer is given to this not unanswerable question. The comparison of the mind to a block of wax, or to a decoy of birds, is found wanting.

But are we not inverting the natural order in looking for opinion before we have found knowledge? And knowledge is not true opinion; for the Athenian dicasts have true opinion but not knowledge. What then is knowledge? We answer (3), 'True opinion, with definition or explanation.' But all the different ways in which this statement may be understood are set aside, like the definitions of courage in the Laches, or of friendship in the Lysis, or of temperance in the Charmides. At length we arrive at the conclusion, in which nothing is concluded.

There are two special difficulties which beset the student of the Theaetetus: (1) he is uncertain how far he can trust Plato's account of the theory of Protagoras; and he is also uncertain (2) how far, and in what parts of the dialogue, Plato is expressing his own opinion. The dramatic character of the work renders the answer to both these questions difficult.

1. In reply to the first, we have only probabilities to offer. Three main points have to be decided: (a) Would Protagoras have identified his own thesis, 'Man is the measure of all things,' with the other, 'All knowledge is sensible perception'? (b) Would he have based the relativity of knowledge on the Heraclitean flux? (c) Would he have asserted the absoluteness of sensation at each instant? Of the work of Protagoras on 'Truth' we know nothing, with the exception of the two famous fragments, which are cited in this dialogue, 'Man is the measure of all things,' and, 'Whether there are gods or not, I cannot tell.' Nor have we any other trustworthy evidence of the tenets of Protagoras, or of the sense in which his words are used. For later writers, including Aristotle in his Metaphysics, have mixed up the Protagoras of Plato, as they have the Socrates of Plato, with the real person.

Returning then to the Theaetetus, as the only possible source from which an answer to these questions can be obtained, we may remark, that Plato had 'The Truth' of Protagoras before him, and frequently refers to the book. He seems to say expressly, that in this work the doctrine of the Heraclitean flux was not to be found; 'he told the real truth' (not in the book, which is so entitled, but) 'privately to his disciples,'—words which imply that the connexion between the doctrines of Protagoras and Heracleitus was not generally recognized in Greece, but was really discovered or invented by Plato. On the other hand, the doctrine that 'Man is the measure of all things,' is expressly identified by Socrates with the other statement, that 'What appears to each man is to him;' and a reference is made to the books in which the statement occurs;—this Theaetetus, who has 'often read the books,' is supposed to acknowledge (so Cratylus). And Protagoras, in the speech attributed to him, never says that he has been misunderstood: he rather seems to imply that the absoluteness of sensation at each instant was to be found in his words. He is only indignant at the 'reductio ad absurdum' devised by Socrates for his 'homo mensura,' which Theodorus also considers to be 'really too bad.'

The question may be raised, how far Plato in the Theaetetus could have misrepresented Protagoras without violating the laws of dramatic probability. Could he have pretended to cite from a well-known writing what was not to be found there? But such a shadowy enquiry is not worth pursuing further. We need only remember that in the criticism which follows of the thesis of Protagoras, we are criticizing the Protagoras of Plato, and not attempting to draw a precise line between his real sentiments and those which Plato has attributed to him.

2. The other difficulty is a more subtle, and also a more important one, because bearing on the general character of the Platonic dialogues. On a first reading of them, we are apt to imagine that the truth is only spoken by Socrates, who is never guilty of a fallacy himself, and is the great detector of the errors and fallacies of others. But this natural presumption is disturbed by the discovery that the Sophists are sometimes in the right and Socrates in the wrong. Like the hero of a novel, he is not to be supposed always to represent the sentiments of the author. There are few modern readers who do not side with Protagoras, rather than with Socrates, in the dialogue which is called by his name. The Cratylus presents a similar difficulty: in his etymologies, as in the number of the State, we cannot tell how far Socrates is serious; for the Socratic irony will not allow him to distinguish between his real and his assumed wisdom. No one is the superior of the invincible Socrates in argument (except in the first part of the Parmenides, where he is introduced as a youth); but he is by no means supposed to be in possession of the whole truth. Arguments are often put into his mouth (compare Introduction to the Gorgias) which must have seemed quite as untenable to Plato as to a modern writer. In this dialogue a great part of the answer of Protagoras is just and sound; remarks are made by him on verbal criticism, and on the importance of understanding an opponent's meaning, which are conceived in the true spirit of philosophy. And the distinction which he is supposed to draw between Eristic and Dialectic, is really a criticism of Plato on himself and his own criticism of Protagoras.

The difficulty seems to arise from not attending to the dramatic character of the writings of Plato. There are two, or more, sides to questions; and these are parted among the different speakers. Sometimes one view or aspect of a question is made to predominate over the rest, as in the Gorgias or Sophist; but in other dialogues truth is divided, as in the Laches and Protagoras, and the interest of the piece consists in the contrast of opinions. The confusion caused by the irony of Socrates, who, if he is true to his character, cannot say anything of his own knowledge, is increased by the circumstance that in the Theaetetus and some other dialogues he is occasionally playing both parts himself, and even charging his own arguments with unfairness. In the Theaetetus he is designedly held back from arriving at a conclusion. For we cannot suppose that Plato conceived a definition of knowledge to be impossible. But this is his manner of approaching and surrounding a question. The lights which he throws on his subject are indirect, but they are not the less real for that. He has no intention of proving a thesis by a cut-and-dried argument; nor does he imagine that a great philosophical problem can be tied up within the limits of a definition. If he has analyzed a proposition or notion, even with the severity of an impossible logic, if half-truths have been compared by him with other half-truths, if he has cleared up or advanced popular ideas, or illustrated a new method, his aim has been sufficiently accomplished.

The writings of Plato belong to an age in which the power of analysis had outrun the means of knowledge; and through a spurious use of dialectic, the distinctions which had been already 'won from the void and formless infinite,' seemed to be rapidly returning to their original chaos. The two great speculative philosophies, which a century earlier had so deeply impressed the mind of Hellas, were now degenerating into Eristic. The contemporaries of Plato and Socrates were vainly trying to find new combinations of them, or to transfer them from the object to the subject. The Megarians, in their first attempts to attain a severer logic, were making knowledge impossible (compare Theaet.). They were asserting 'the one good under many names,' and, like the Cynics, seem to have denied predication, while the Cynics themselves were depriving virtue of all which made virtue desirable in the eyes of Socrates and Plato. And besides these, we find mention in the later writings of Plato, especially in the Theaetetus, Sophist, and Laws, of certain impenetrable godless persons, who will not believe what they 'cannot hold in their hands'; and cannot be approached in argument, because they cannot argue (Theat; Soph.). No school of Greek philosophers exactly answers to these persons, in whom Plato may perhaps have blended some features of the Atomists with the vulgar materialistic tendencies of mankind in general (compare Introduction to the Sophist).

And not only was there a conflict of opinions, but the stage which the mind had reached presented other difficulties hardly intelligible to us, who live in a different cycle of human thought. All times of mental progress are times of confusion; we only see, or rather seem to see things clearly, when they have been long fixed and defined. In the age of Plato, the limits of the world of imagination and of pure abstraction, of the old world and the new, were not yet fixed. The Greeks, in the fourth century before Christ, had no words for 'subject' and 'object,' and no distinct conception of them; yet they were always hovering about the question involved in them. The analysis of sense, and the analysis of thought, were equally difficult to them; and hopelessly confused by the attempt to solve them, not through an appeal to facts, but by the help of general theories respecting the nature of the universe.

Plato, in his Theaetetus, gathers up the sceptical tendencies of his age, and compares them. But he does not seek to reconstruct out of them a theory of knowledge. The time at which such a theory could be framed had not yet arrived. For there was no measure of experience with which the ideas swarming in men's minds could be compared; the meaning of the word 'science' could scarcely be explained to them, except from the mathematical sciences, which alone offered the type of universality and certainty. Philosophy was becoming more and more vacant and abstract, and not only the Platonic Ideas and the Eleatic Being, but all abstractions seemed to be at variance with sense and at war with one another.

The want of the Greek mind in the fourth century before Christ was not another theory of rest or motion, or Being or atoms, but rather a philosophy which could free the mind from the power of abstractions and alternatives, and show how far rest and how far motion, how far the universal principle of Being and the multitudinous principle of atoms, entered into the composition of the world; which could distinguish between the true and false analogy, and allow the negative as well as the positive a place in human thought. To such a philosophy Plato, in the Theaetetus, offers many contributions. He has followed philosophy into the region of mythology, and pointed out the similarities of opposing phases of thought. He has also shown that extreme abstractions are self-destructive, and, indeed, hardly distinguishable from one another. But his intention is not to unravel the whole subject of knowledge, if this had been possible; and several times in the course of the dialogue he rejects explanations of knowledge which have germs of truth in them; as, for example, 'the resolution of the compound into the simple;' or 'right opinion with a mark of difference.'

...

Terpsion, who has come to Megara from the country, is described as having looked in vain for Euclides in the Agora; the latter explains that he has been down to the harbour, and on his way thither had met Theaetetus, who was being carried up from the army to Athens. He was scarcely alive, for he had been badly wounded at the battle of Corinth, and had taken the dysentery which prevailed in the camp. The mention of his condition suggests the reflection, 'What a loss he will be!' 'Yes, indeed,' replies Euclid; 'only just now I was hearing of his noble conduct in the battle.' 'That I should expect; but why did he not remain at Megara?' 'I wanted him to remain, but he would not; so I went with him as far as Erineum; and as I parted from him, I remembered that Socrates had seen him when he was a youth, and had a remarkable conversation with him, not long before his own death; and he then prophesied of him that he would be a great man if he lived.' 'How true that has been; how like all that Socrates said! And could you repeat the conversation?' 'Not from memory; but I took notes when I returned home, which I afterwards filled up at leisure, and got Socrates to correct them from time to time, when I came to Athens'...Terpsion had long intended to ask for a sight of this writing, of which he had already heard. They are both tired, and agree to rest and have the conversation read to them by a servant...'Here is the roll, Terpsion; I need only observe that I have omitted, for the sake of convenience, the interlocutory words, "said I," "said he"; and that Theaetetus, and Theodorus, the geometrician of Cyrene, are the persons with whom Socrates is conversing.'

Socrates begins by asking Theodorus whether, in his visit to Athens, he has found any Athenian youth likely to attain distinction in science. 'Yes, Socrates, there is one very remarkable youth, with whom I have become acquainted. He is no beauty, and therefore you need not imagine that I am in love with him; and, to say the truth, he is very like you, for he has a snub nose, and projecting eyes, although these features are not so marked in him as in you. He combines the most various qualities, quickness, patience, courage; and he is gentle as well as wise, always silently flowing on, like a river of oil. Look! he is the middle one of those who are entering the palaestra.'

Socrates, who does not know his name, recognizes him as the son of Euphronius, who was himself a good man and a rich. He is informed by Theodorus that the youth is named Theaetetus, but the property of his father has disappeared in the hands of trustees; this does not, however, prevent him from adding liberality to his other virtues. At the desire of Socrates he invites Theaetetus to sit by them.

'Yes,' says Socrates, 'that I may see in you, Theaetetus, the image of my ugly self, as Theodorus declares. Not that his remark is of any importance; for though he is a philosopher, he is not a painter, and therefore he is no judge of our faces; but, as he is a man of science, he may be a judge of our intellects. And if he were to praise the mental endowments of either of us, in that case the hearer of the eulogy ought to examine into what he says, and the subject should not refuse to be examined.' Theaetetus consents, and is caught in a trap (compare the similar trap which is laid for Theodorus). 'Then, Theaetetus, you will have to be examined, for Theodorus has been praising you in a style of which I never heard the like.' 'He was only jesting.' 'Nay, that is not his way; and I cannot allow you, on that pretence, to retract the assent which you have already given, or I shall make Theodorus repeat your praises, and swear to them.' Theaetetus, in reply, professes that he is willing to be examined, and Socrates begins by asking him what he learns of Theodorus. He is himself anxious to learn anything of anybody; and now he has a little question to which he wants Theaetetus or Theodorus (or whichever of the company would not be 'donkey' to the rest) to find an answer. Without further preface, but at the same time apologizing for his eagerness, he asks, 'What is knowledge?' Theodorus is too old to answer questions, and begs him to interrogate Theaetetus, who has the advantage of youth.

Theaetetus replies, that knowledge is what he learns of Theodorus, i.e. geometry and arithmetic; and that there are other kinds of knowledge—shoemaking, carpentering, and the like. But Socrates rejoins, that this answer contains too much and also too little. For although Theaetetus has enumerated several kinds of knowledge, he has not explained the common nature of them; as if he had been asked, 'What is clay?' and instead of saying 'Clay is moistened earth,' he had answered, 'There is one clay of image-makers, another of potters, another of oven-makers.' Theaetetus at once divines that Socrates means him to extend to all kinds of knowledge the same process of generalization which he has already learned to apply to arithmetic. For he has discovered a division of numbers into square numbers, 4, 9, 16, etc., which are composed of equal factors, and represent figures which have equal sides, and oblong numbers, 3, 5, 6, 7, etc., which are composed of unequal factors, and represent figures which have unequal sides. But he has never succeeded in attaining a similar conception of knowledge, though he has often tried; and, when this and similar questions were brought to him from Socrates, has been sorely distressed by them. Socrates explains to him that he is in labour. For men as well as women have pangs of labour; and both at times require the assistance of midwives. And he, Socrates, is a midwife, although this is a secret; he has inherited the art from his mother bold and bluff, and he ushers into light, not children, but the thoughts of men. Like the midwives, who are 'past bearing children,' he too can have no offspring—the God will not allow him to bring anything into the world of his own. He also reminds Theaetetus that the midwives are or ought to be the only matchmakers (this is the preparation for a biting jest); for those who reap the fruit are most likely to know on what soil the plants will grow. But respectable midwives avoid this department of practice—they do not want to be called procuresses. There are some other differences between the two sorts of pregnancy. For women do not bring into the world at one time real children and at another time idols which are with difficulty distinguished from them. 'At first,' says Socrates in his character of the man-midwife, 'my patients are barren and stolid, but after a while they "round apace," if the gods are propitious to them; and this is due not to me but to themselves; I and the god only assist in bringing their ideas to the birth. Many of them have left me too soon, and the result has been that they have produced abortions; or when I have delivered them of children they have lost them by an ill bringing up, and have ended by seeing themselves, as others see them, to be great fools. Aristides, the son of Lysimachus, is one of these, and there have been others. The truants often return to me and beg to be taken back; and then, if my familiar allows me, which is not always the case, I receive them, and they begin to grow again. There come to me also those who have nothing in them, and have no need of my art; and I am their matchmaker (see above), and marry them to Prodicus or some other inspired sage who is likely to suit them. I tell you this long story because I suspect that you are in labour. Come then to me, who am a midwife, and the son of a midwife, and I will deliver you. And do not bite me, as the women do, if I abstract your first-born; for I am acting out of good-will towards you; the God who is within me is the friend of man, though he will not allow me to dissemble the truth. Once more then, Theaetetus, I repeat my old question—"What is knowledge?" Take courage, and by the help of God you will discover an answer.' 'My answer is, that knowledge is perception.' 'That is the theory of Protagoras, who has another way of expressing the same thing when he says, "Man is the measure of all things." He was a very wise man, and we should try to understand him. In order to illustrate his meaning let me suppose that there is the same wind blowing in our faces, and one of us may be hot and the other cold. How is this? Protagoras will reply that the wind is hot to him who is cold, cold to him who is hot. And "is" means "appears," and when you say "appears to him," that means "he feels." Thus feeling, appearance, perception, coincide with being. I suspect, however, that this was only a "facon de parler," by which he imposed on the common herd like you and me; he told "the truth" (in allusion to the title of his book, which was called "The Truth") in secret to his disciples. For he was really a votary of that famous philosophy in which all things are said to be relative; nothing is great or small, or heavy or light, or one, but all is in motion and mixture and transition and flux and generation, not "being," as we ignorantly affirm, but "becoming." This has been the doctrine, not of Protagoras only, but of all philosophers, with the single exception of Parmenides; Empedocles, Heracleitus, and others, and all the poets, with Epicharmus, the king of Comedy, and Homer, the king of Tragedy, at their head, have said the same; the latter has these words—

"Ocean, whence the gods sprang, and mother Tethys."

And many arguments are used to show, that motion is the source of life, and rest of death: fire and warmth are produced by friction, and living creatures owe their origin to a similar cause; the bodily frame is preserved by exercise and destroyed by indolence; and if the sun ceased to move, "chaos would come again." Now apply this doctrine of "All is motion" to the senses, and first of all to the sense of sight. The colour of white, or any other colour, is neither in the eyes nor out of them, but ever in motion between the object and the eye, and varying in the case of every percipient. All is relative, and, as the followers of Protagoras remark, endless contradictions arise when we deny this; e.g. here are six dice; they are more than four and less than twelve; "more and also less," would you not say?' 'Yes.' 'But Protagoras will retort: "Can anything be more or less without addition or subtraction?"'

'I should say "No" if I were not afraid of contradicting my former answer.'

'And if you say "Yes," the tongue will escape conviction but not the mind, as Euripides would say?' 'True.' 'The thoroughbred Sophists, who know all that can be known, would have a sparring match over this, but you and I, who have no professional pride, want only to discover whether our ideas are clear and consistent. And we cannot be wrong in saying, first, that nothing can be greater or less while remaining equal; secondly, that there can be no becoming greater or less without addition or subtraction; thirdly, that what is and was not, cannot be without having become. But then how is this reconcilable with the case of the dice, and with similar examples?—that is the question.' 'I am often perplexed and amazed, Socrates, by these difficulties.' 'That is because you are a philosopher, for philosophy begins in wonder, and Iris is the child of Thaumas. Do you know the original principle on which the doctrine of Protagoras is based?' 'No.' 'Then I will tell you; but we must not let the uninitiated hear, and by the uninitiated I mean the obstinate people who believe in nothing which they cannot hold in their hands. The brethren whose mysteries I am about to unfold to you are far more ingenious. They maintain that all is motion; and that motion has two forms, action and passion, out of which endless phenomena are created, also in two forms—sense and the object of sense—which come to the birth together. There are two kinds of motions, a slow and a fast; the motions of the agent and the patient are slower, because they move and create in and about themselves, but the things which are born of them have a swifter motion, and pass rapidly from place to place. The eye and the appropriate object come together, and give birth to whiteness and the sensation of whiteness; the eye is filled with seeing, and becomes not sight but a seeing eye, and the object is filled with whiteness, and becomes not whiteness but white; and no other compound of either with another would have produced the same effect. All sensation is to be resolved into a similar combination of an agent and patient. Of either, taken separately, no idea can be formed; and the agent may become a patient, and the patient an agent. Hence there arises a general reflection that nothing is, but all things become; no name can detain or fix them. Are not these speculations charming, Theaetetus, and very good for a person in your interesting situation? I am offering you specimens of other men's wisdom, because I have no wisdom of my own, and I want to deliver you of something; and presently we will see whether you have brought forth wind or not. Tell me, then, what do you think of the notion that "All things are becoming"?'

'When I hear your arguments, I am marvellously ready to assent.'

'But I ought not to conceal from you that there is a serious objection which may be urged against this doctrine of Protagoras. For there are states, such as madness and dreaming, in which perception is false; and half our life is spent in dreaming; and who can say that at this instant we are not dreaming? Even the fancies of madmen are real at the time. But if knowledge is perception, how can we distinguish between the true and the false in such cases? Having stated the objection, I will now state the answer. Protagoras would deny the continuity of phenomena; he would say that what is different is entirely different, and whether active or passive has a different power. There are infinite agents and patients in the world, and these produce in every combination of them a different perception. Take myself as an instance:—Socrates may be ill or he may be well,—and remember that Socrates, with all his accidents, is spoken of. The wine which I drink when I am well is pleasant to me, but the same wine is unpleasant to me when I am ill. And there is nothing else from which I can receive the same impression, nor can another receive the same impression from the wine. Neither can I and the object of sense become separately what we become together. For the one in becoming is relative to the other, but they have no other relation; and the combination of them is absolute at each moment. (In modern language, the act of sensation is really indivisible, though capable of a mental analysis into subject and object.) My sensation alone is true, and true to me only. And therefore, as Protagoras says, "To myself I am the judge of what is and what is not." Thus the flux of Homer and Heracleitus, the great Protagorean saying that "Man is the measure of all things," the doctrine of Theaetetus that "Knowledge is perception," have all the same meaning. And this is thy new-born child, which by my art I have brought to light; and you must not be angry if instead of rearing your infant we expose him.'

'Theaetetus will not be angry,' says Theodorus; 'he is very good-natured. But I should like to know, Socrates, whether you mean to say that all this is untrue?'

'First reminding you that I am not the bag which contains the arguments, but that I extract them from Theaetetus, shall I tell you what amazes me in your friend Protagoras?'

'What may that be?'

'I like his doctrine that what appears is; but I wonder that he did not begin his great work on Truth with a declaration that a pig, or a dog-faced baboon, or any other monster which has sensation, is a measure of all things; then, while we were reverencing him as a god, he might have produced a magnificent effect by expounding to us that he was no wiser than a tadpole. For if sensations are always true, and one man's discernment is as good as another's, and every man is his own judge, and everything that he judges is right and true, then what need of Protagoras to be our instructor at a high figure; and why should we be less knowing than he is, or have to go to him, if every man is the measure of all things? My own art of midwifery, and all dialectic, is an enormous folly, if Protagoras' "Truth" be indeed truth, and the philosopher is not merely amusing himself by giving oracles out of his book.'

Theodorus thinks that Socrates is unjust to his master, Protagoras; but he is too old and stiff to try a fall with him, and therefore refers him to Theaetetus, who is already driven out of his former opinion by the arguments of Socrates.

Socrates then takes up the defence of Protagoras, who is supposed to reply in his own person—'Good people, you sit and declaim about the gods, of whose existence or non-existence I have nothing to say, or you discourse about man being reduced to the level of the brutes; but what proof have you of your statements? And yet surely you and Theodorus had better reflect whether probability is a safe guide. Theodorus would be a bad geometrician if he had nothing better to offer.'...Theaetetus is affected by the appeal to geometry, and Socrates is induced by him to put the question in a new form. He proceeds as follows:—'Should we say that we know what we see and hear,—e.g. the sound of words or the sight of letters in a foreign tongue?'

'We should say that the figures of the letters, and the pitch of the voice in uttering them, were known to us, but not the meaning of them.'

'Excellent; I want you to grow, and therefore I will leave that answer and ask another question: Is not seeing perceiving?' 'Very true.' 'And he who sees knows?' 'Yes.' 'And he who remembers, remembers that which he sees and knows?' 'Very true.' 'But if he closes his eyes, does he not remember?' 'He does.' 'Then he may remember and not see; and if seeing is knowing, he may remember and not know. Is not this a "reductio ad absurdum" of the hypothesis that knowledge is sensible perception? Yet perhaps we are crowing too soon; and if Protagoras, "the father of the myth," had been alive, the result might have been very different. But he is dead, and Theodorus, whom he left guardian of his "orphan," has not been very zealous in defending him.'

Theodorus objects that Callias is the true guardian, but he hopes that Socrates will come to the rescue. Socrates prefaces his defence by resuming the attack. He asks whether a man can know and not know at the same time? 'Impossible.' Quite possible, if you maintain that seeing is knowing. The confident adversary, suiting the action to the word, shuts one of your eyes; and now, says he, you see and do not see, but do you know and not know? And a fresh opponent darts from his ambush, and transfers to knowledge the terms which are commonly applied to sight. He asks whether you can know near and not at a distance; whether you can have a sharp and also a dull knowledge. While you are wondering at his incomparable wisdom, he gets you into his power, and you will not escape until you have come to an understanding with him about the money which is to be paid for your release.

But Protagoras has not yet made his defence; and already he may be heard contemptuously replying that he is not responsible for the admissions which were made by a boy, who could not foresee the coming move, and therefore had answered in a manner which enabled Socrates to raise a laugh against himself. 'But I cannot be fairly charged,' he will say, 'with an answer which I should not have given; for I never maintained that the memory of a feeling is the same as a feeling, or denied that a man might know and not know the same thing at the same time. Or, if you will have extreme precision, I say that man in different relations is many or rather infinite in number. And I challenge you, either to show that his perceptions are not individual, or that if they are, what appears to him is not what is. As to your pigs and baboons, you are yourself a pig, and you make my writings a sport of other swine. But I still affirm that man is the measure of all things, although I admit that one man may be a thousand times better than another, in proportion as he has better impressions. Neither do I deny the existence of wisdom or of the wise man. But I maintain that wisdom is a practical remedial power of turning evil into good, the bitterness of disease into the sweetness of health, and does not consist in any greater truth or superior knowledge. For the impressions of the sick are as true as the impressions of the healthy; and the sick are as wise as the healthy. Nor can any man be cured of a false opinion, for there is no such thing; but he may be cured of the evil habit which generates in him an evil opinion. This is effected in the body by the drugs of the physician, and in the soul by the words of the Sophist; and the new state or opinion is not truer, but only better than the old. And philosophers are not tadpoles, but physicians and husbandmen, who till the soil and infuse health into animals and plants, and make the good take the place of the evil, both in individuals and states. Wise and good rhetoricians make the good to appear just in states (for that is just which appears just to a state), and in return, they deserve to be well paid. And you, Socrates, whether you please or not, must continue to be a measure. This is my defence, and I must request you to meet me fairly. We are professing to reason, and not merely to dispute; and there is a great difference between reasoning and disputation. For the disputer is always seeking to trip up his opponent; and this is a mode of argument which disgusts men with philosophy as they grow older. But the reasoner is trying to understand him and to point out his errors to him, whether arising from his own or from his companion's fault; he does not argue from the customary use of names, which the vulgar pervert in all manner of ways. If you are gentle to an adversary he will follow and love you; and if defeated he will lay the blame on himself, and seek to escape from his own prejudices into philosophy. I would recommend you, Socrates, to adopt this humaner method, and to avoid captious and verbal criticisms.'

Such, Theodorus, is the very slight help which I am able to afford to your friend; had he been alive, he would have helped himself in far better style.

'You have made a most valorous defence.'

Yes; but did you observe that Protagoras bade me be serious, and complained of our getting up a laugh against him with the aid of a boy? He meant to intimate that you must take the place of Theaetetus, who may be wiser than many bearded men, but not wiser than you, Theodorus.

'The rule of the Spartan Palaestra is, Strip or depart; but you are like the giant Antaeus, and will not let me depart unless I try a fall with you.'

Yes, that is the nature of my complaint. And many a Hercules, many a Theseus mighty in deeds and words has broken my head; but I am always at this rough game. Please, then, to favour me.

'On the condition of not exceeding a single fall, I consent.'

Socrates now resumes the argument. As he is very desirous of doing justice to Protagoras, he insists on citing his own words,—'What appears to each man is to him.' And how, asks Socrates, are these words reconcileable with the fact that all mankind are agreed in thinking themselves wiser than others in some respects, and inferior to them in others? In the hour of danger they are ready to fall down and worship any one who is their superior in wisdom as if he were a god. And the world is full of men who are asking to be taught and willing to be ruled, and of other men who are willing to rule and teach them. All which implies that men do judge of one another's impressions, and think some wise and others foolish. How will Protagoras answer this argument? For he cannot say that no one deems another ignorant or mistaken. If you form a judgment, thousands and tens of thousands are ready to maintain the opposite. The multitude may not and do not agree in Protagoras' own thesis that 'Man is the measure of all things;' and then who is to decide? Upon his own showing must not his 'truth' depend on the number of suffrages, and be more or less true in proportion as he has more or fewer of them? And he must acknowledge further, that they speak truly who deny him to speak truly, which is a famous jest. And if he admits that they speak truly who deny him to speak truly, he must admit that he himself does not speak truly. But his opponents will refuse to admit this of themselves, and he must allow that they are right in their refusal. The conclusion is, that all mankind, including Protagoras himself, will deny that he speaks truly; and his truth will be true neither to himself nor to anybody else.

Theodorus is inclined to think that this is going too far. Socrates ironically replies, that he is not going beyond the truth. But if the old Protagoras could only pop his head out of the world below, he would doubtless give them both a sound castigation and be off to the shades in an instant. Seeing that he is not within call, we must examine the question for ourselves. It is clear that there are great differences in the understandings of men. Admitting, with Protagoras, that immediate sensations of hot, cold, and the like, are to each one such as they appear, yet this hypothesis cannot be extended to judgments or opinions. And even if we were to admit further,—and this is the view of some who are not thorough-going followers of Protagoras,—that right and wrong, holy and unholy, are to each state or individual such as they appear, still Protagoras will not venture to maintain that every man is equally the measure of expediency, or that the thing which seems is expedient to every one. But this begins a new question. 'Well, Socrates, we have plenty of leisure. Yes, we have, and, after the manner of philosophers, we are digressing; I have often observed how ridiculous this habit of theirs makes them when they appear in court. 'What do you mean?' I mean to say that a philosopher is a gentleman, but a lawyer is a servant. The one can have his talk out, and wander at will from one subject to another, as the fancy takes him; like ourselves, he may be long or short, as he pleases. But the lawyer is always in a hurry; there is the clepsydra limiting his time, and the brief limiting his topics, and his adversary is standing over him and exacting his rights. He is a servant disputing about a fellow-servant before his master, who holds the cause in his hands; the path never diverges, and often the race is for his life. Such experiences render him keen and shrewd; he learns the arts of flattery, and is perfect in the practice of crooked ways; dangers have come upon him too soon, when the tenderness of youth was unable to meet them with truth and honesty, and he has resorted to counter-acts of dishonesty and falsehood, and become warped and distorted; without any health or freedom or sincerity in him he has grown up to manhood, and is or esteems himself to be a master of cunning. Such are the lawyers; will you have the companion picture of philosophers? or will this be too much of a digression?

'Nay, Socrates, the argument is our servant, and not our master. Who is the judge or where is the spectator, having a right to control us?'

I will describe the leaders, then: for the inferior sort are not worth the trouble. The lords of philosophy have not learned the way to the dicastery or ecclesia; they neither see nor hear the laws and votes of the state, written or recited; societies, whether political or festive, clubs, and singing maidens do not enter even into their dreams. And the scandals of persons or their ancestors, male and female, they know no more than they can tell the number of pints in the ocean. Neither are they conscious of their own ignorance; for they do not practise singularity in order to gain reputation, but the truth is, that the outer form of them only is residing in the city; the inner man, as Pindar says, is going on a voyage of discovery, measuring as with line and rule the things which are under and in the earth, interrogating the whole of nature, only not condescending to notice what is near them.

'What do you mean, Socrates?'

I will illustrate my meaning by the jest of the witty maid-servant, who saw Thales tumbling into a well, and said of him, that he was so eager to know what was going on in heaven, that he could not see what was before his feet. This is applicable to all philosophers. The philosopher is unacquainted with the world; he hardly knows whether his neighbour is a man or an animal. For he is always searching into the essence of man, and enquiring what such a nature ought to do or suffer different from any other. Hence, on every occasion in private life and public, as I was saying, when he appears in a law-court or anywhere, he is the joke, not only of maid-servants, but of the general herd, falling into wells and every sort of disaster; he looks such an awkward, inexperienced creature, unable to say anything personal, when he is abused, in answer to his adversaries (for he knows no evil of any one); and when he hears the praises of others, he cannot help laughing from the bottom of his soul at their pretensions; and this also gives him a ridiculous appearance. A king or tyrant appears to him to be a kind of swine-herd or cow-herd, milking away at an animal who is much more troublesome and dangerous than cows or sheep; like the cow-herd, he has no time to be educated, and the pen in which he keeps his flock in the mountains is surrounded by a wall. When he hears of large landed properties of ten thousand acres or more, he thinks of the whole earth; or if he is told of the antiquity of a family, he remembers that every one has had myriads of progenitors, rich and poor, Greeks and barbarians, kings and slaves. And he who boasts of his descent from Amphitryon in the twenty-fifth generation, may, if he pleases, add as many more, and double that again, and our philosopher only laughs at his inability to do a larger sum. Such is the man at whom the vulgar scoff; he seems to them as if he could not mind his feet. 'That is very true, Socrates.' But when he tries to draw the quick-witted lawyer out of his pleas and rejoinders to the contemplation of absolute justice or injustice in their own nature, or from the popular praises of wealthy kings to the view of happiness and misery in themselves, or to the reasons why a man should seek after the one and avoid the other, then the situation is reversed; the little wretch turns giddy, and is ready to fall over the precipice; his utterance becomes thick, and he makes himself ridiculous, not to servant-maids, but to every man of liberal education. Such are the two pictures: the one of the philosopher and gentleman, who may be excused for not having learned how to make a bed, or cook up flatteries; the other, a serviceable knave, who hardly knows how to wear his cloak,—still less can he awaken harmonious thoughts or hymn virtue's praises.

'If the world, Socrates, were as ready to receive your words as I am, there would be greater peace and less evil among mankind.'

Evil, Theodorus, must ever remain in this world to be the antagonist of good, out of the way of the gods in heaven. Wherefore also we should fly away from ourselves to them; and to fly to them is to become like them; and to become like them is to become holy, just and true. But many live in the old wives' fable of appearances; they think that you should follow virtue in order that you may seem to be good. And yet the truth is, that God is righteous; and of men, he is most like him who is most righteous. To know this is wisdom; and in comparison of this the wisdom of the arts or the seeming wisdom of politicians is mean and common. The unrighteous man is apt to pride himself on his cunning; when others call him rogue, he says to himself: 'They only mean that I am one who deserves to live, and not a mere burden of the earth.' But he should reflect that his ignorance makes his condition worse than if he knew. For the penalty of injustice is not death or stripes, but the fatal necessity of becoming more and more unjust. Two patterns of life are set before him; the one blessed and divine, the other godless and wretched; and he is growing more and more like the one and unlike the other. He does not see that if he continues in his cunning, the place of innocence will not receive him after death. And yet if such a man has the courage to hear the argument out, he often becomes dissatisfied with himself, and has no more strength in him than a child.—But we have digressed enough.

'For my part, Socrates, I like the digressions better than the argument, because I understand them better.'

To return. When we left off, the Protagoreans and Heracliteans were maintaining that the ordinances of the State were just, while they lasted. But no one would maintain that the laws of the State were always good or expedient, although this may be the intention of them. For the expedient has to do with the future, about which we are liable to mistake. Now, would Protagoras maintain that man is the measure not only of the present and past, but of the future; and that there is no difference in the judgments of men about the future? Would an untrained man, for example, be as likely to know when he is going to have a fever, as the physician who attended him? And if they differ in opinion, which of them is likely to be right; or are they both right? Is not a vine-grower a better judge of a vintage which is not yet gathered, or a cook of a dinner which is in preparation, or Protagoras of the probable effect of a speech than an ordinary person? The last example speaks 'ad hominen.' For Protagoras would never have amassed a fortune if every man could judge of the future for himself. He is, therefore, compelled to admit that he is a measure; but I, who know nothing, am not equally convinced that I am. This is one way of refuting him; and he is refuted also by the authority which he attributes to the opinions of others, who deny his opinions. I am not equally sure that we can disprove the truth of immediate states of feeling. But this leads us to the doctrine of the universal flux, about which a battle-royal is always going on in the cities of Ionia. 'Yes; the Ephesians are downright mad about the flux; they cannot stop to argue with you, but are in perpetual motion, obedient to their text-books. Their restlessness is beyond expression, and if you ask any of them a question, they will not answer, but dart at you some unintelligible saying, and another and another, making no way either with themselves or with others; for nothing is fixed in them or their ideas,—they are at war with fixed principles.' I suppose, Theodorus, that you have never seen them in time of peace, when they discourse at leisure to their disciples? 'Disciples! they have none; they are a set of uneducated fanatics, and each of them says of the other that they have no knowledge. We must trust to ourselves, and not to them for the solution of the problem.' Well, the doctrine is old, being derived from the poets, who speak in a figure of Oceanus and Tethys; the truth was once concealed, but is now revealed by the superior wisdom of a later generation, and made intelligible to the cobbler, who, on hearing that all is in motion, and not some things only, as he ignorantly fancied, may be expected to fall down and worship his teachers. And the opposite doctrine must not be forgotten:—

as Parmenides affirms. Thus we are in the midst of the fray; both parties are dragging us to their side; and we are not certain which of them are in the right; and if neither, then we shall be in a ridiculous position, having to set up our own opinion against ancient and famous men.

Let us first approach the river-gods, or patrons of the flux.

When they speak of motion, must they not include two kinds of motion, change of place and change of nature?—And all things must be supposed to have both kinds of motion; for if not, the same things would be at rest and in motion, which is contrary to their theory. And did we not say, that all sensations arise thus: they move about between the agent and patient together with a perception, and the patient ceases to be a perceiving power and becomes a percipient, and the agent a quale instead of a quality; but neither has any absolute existence? But now we make the further discovery, that neither white or whiteness, nor any sense or sensation, can be predicated of anything, for they are in a perpetual flux. And therefore we must modify the doctrine of Theaetetus and Protagoras, by asserting further that knowledge is and is not sensation; and of everything we must say equally, that this is and is not, or becomes or becomes not. And still the word 'this' is not quite correct, for language fails in the attempt to express their meaning.

At the close of the discussion, Theodorus claims to be released from the argument, according to his agreement. But Theaetetus insists that they shall proceed to consider the doctrine of rest. This is declined by Socrates, who has too much reverence for the great Parmenides lightly to attack him. (We shall find that he returns to the doctrine of rest in the Sophist; but at present he does not wish to be diverted from his main purpose, which is, to deliver Theaetetus of his conception of knowledge.) He proceeds to interrogate him further. When he says that 'knowledge is in perception,' with what does he perceive? The first answer is, that he perceives sights with the eye, and sounds with the ear. This leads Socrates to make the reflection that nice distinctions of words are sometimes pedantic, but sometimes necessary; and he proposes in this case to substitute the word 'through' for 'with.' For the senses are not like the Trojan warriors in the horse, but have a common centre of perception, in which they all meet. This common principle is able to compare them with one another, and must therefore be distinct from them (compare Republic). And as there are facts of sense which are perceived through the organs of the body, there are also mathematical and other abstractions, such as sameness and difference, likeness and unlikeness, which the soul perceives by herself. Being is the most universal of these abstractions. The good and the beautiful are abstractions of another kind, which exist in relation and which above all others the mind perceives in herself, comparing within her past, present, and future. For example; we know a thing to be hard or soft by the touch, of which the perception is given at birth to men and animals. But the essence of hardness or softness, or the fact that this hardness is, and is the opposite of softness, is slowly learned by reflection and experience. Mere perception does not reach being, and therefore fails of truth; and therefore has no share in knowledge. But if so, knowledge is not perception. What then is knowledge? The mind, when occupied by herself with being, is said to have opinion—shall we say that 'Knowledge is true opinion'? But still an old difficulty recurs; we ask ourselves, 'How is false opinion possible?' This difficulty may be stated as follows:—

Either we know or do not know a thing (for the intermediate processes of learning and forgetting need not at present be considered); and in thinking or having an opinion, we must either know or not know that which we think, and we cannot know and be ignorant at the same time; we cannot confuse one thing which we do not know, with another thing which we do not know; nor can we think that which we do not know to be that which we know, or that which we know to be that which we do not know. And what other case is conceivable, upon the supposition that we either know or do not know all things? Let us try another answer in the sphere of being: 'When a man thinks, and thinks that which is not.' But would this hold in any parallel case? Can a man see and see nothing? or hear and hear nothing? or touch and touch nothing? Must he not see, hear, or touch some one existing thing? For if he thinks about nothing he does not think, and not thinking he cannot think falsely. And so the path of being is closed against us, as well as the path of knowledge. But may there not be 'heterodoxy,' or transference of opinion;—I mean, may not one thing be supposed to be another? Theaetetus is confident that this must be 'the true falsehood,' when a man puts good for evil or evil for good. Socrates will not discourage him by attacking the paradoxical expression 'true falsehood,' but passes on. The new notion involves a process of thinking about two things, either together or alternately. And thinking is the conversing of the mind with herself, which is carried on in question and answer, until she no longer doubts, but determines and forms an opinion. And false opinion consists in saying to yourself, that one thing is another. But did you ever say to yourself, that good is evil, or evil good? Even in sleep, did you ever imagine that odd was even? Or did any man in his senses ever fancy that an ox was a horse, or that two are one? So that we can never think one thing to be another; for you must not meet me with the verbal quibble that one—eteron—is other—eteron (both 'one' and 'other' in Greek are called 'other'—eteron). He who has both the two things in his mind, cannot misplace them; and he who has only one of them in his mind, cannot misplace them—on either supposition transplacement is inconceivable.

But perhaps there may still be a sense in which we can think that which we do not know to be that which we know: e.g. Theaetetus may know Socrates, but at a distance he may mistake another person for him. This process may be conceived by the help of an image. Let us suppose that every man has in his mind a block of wax of various qualities, the gift of Memory, the mother of the Muses; and on this he receives the seal or stamp of those sensations and perceptions which he wishes to remember. That which he succeeds in stamping is remembered and known by him as long as the impression lasts; but that, of which the impression is rubbed out or imperfectly made, is forgotten, and not known. No one can think one thing to be another, when he has the memorial or seal of both of these in his soul, and a sensible impression of neither; or when he knows one and does not know the other, and has no memorial or seal of the other; or when he knows neither; or when he perceives both, or one and not the other, or neither; or when he perceives and knows both, and identifies what he perceives with what he knows (this is still more impossible); or when he does not know one, and does not know and does not perceive the other; or does not perceive one, and does not know and does not perceive the other; or has no perception or knowledge of either—all these cases must be excluded. But he may err when he confuses what he knows or perceives, or what he perceives and does not know, with what he knows, or what he knows and perceives with what he knows and perceives.

Theaetetus is unable to follow these distinctions; which Socrates proceeds to illustrate by examples, first of all remarking, that knowledge may exist without perception, and perception without knowledge. I may know Theodorus and Theaetetus and not see them; I may see them, and not know them. 'That I understand.' But I could not mistake one for the other if I knew you both, and had no perception of either; or if I knew one only, and perceived neither; or if I knew and perceived neither, or in any other of the excluded cases. The only possibility of error is: 1st, when knowing you and Theodorus, and having the impression of both of you on the waxen block, I, seeing you both imperfectly and at a distance, put the foot in the wrong shoe—that is to say, put the seal or stamp on the wrong object: or 2ndly, when knowing both of you I only see one; or when, seeing and knowing you both, I fail to identify the impression and the object. But there could be no error when perception and knowledge correspond.

The waxen block in the heart of a man's soul, as I may say in the words of Homer, who played upon the words ker and keros, may be smooth and deep, and large enough, and then the signs are clearly marked and lasting, and do not get confused. But in the 'hairy heart,' as the all-wise poet sings, when the wax is muddy or hard or moist, there is a corresponding confusion and want of retentiveness; in the muddy and impure there is indistinctness, and still more in the hard, for there the impressions have no depth of wax, and in the moist they are too soon effaced. Yet greater is the indistinctness when they are all jolted together in a little soul, which is narrow and has no room. These are the sort of natures which have false opinion; from stupidity they see and hear and think amiss; and this is falsehood and ignorance. Error, then, is a confusion of thought and sense.

Theaetetus is delighted with this explanation. But Socrates has no sooner found the new solution than he sinks into a fit of despondency. For an objection occurs to him:—May there not be errors where there is no confusion of mind and sense? e.g. in numbers. No one can confuse the man whom he has in his thoughts with the horse which he has in his thoughts, but he may err in the addition of five and seven. And observe that these are purely mental conceptions. Thus we are involved once more in the dilemma of saying, either that there is no such thing as false opinion, or that a man knows what he does not know.

We are at our wit's end, and may therefore be excused for making a bold diversion. All this time we have been repeating the words 'know,' 'understand,' yet we do not know what knowledge is. 'Why, Socrates, how can you argue at all without using them?' Nay, but the true hero of dialectic would have forbidden me to use them until I had explained them. And I must explain them now. The verb 'to know' has two senses, to have and to possess knowledge, and I distinguish 'having' from 'possessing.' A man may possess a garment which he does not wear; or he may have wild birds in an aviary; these in one sense he possesses, and in another he has none of them. Let this aviary be an image of the mind, as the waxen block was; when we are young, the aviary is empty; after a time the birds are put in; for under this figure we may describe different forms of knowledge;—there are some of them in groups, and some single, which are flying about everywhere; and let us suppose a hunt after the science of odd and even, or some other science. The possession of the birds is clearly not the same as the having them in the hand. And the original chase of them is not the same as taking them in the hand when they are already caged.

This distinction between use and possession saves us from the absurdity of supposing that we do not know what we know, because we may know in one sense, i.e. possess, what we do not know in another, i.e. use. But have we not escaped one difficulty only to encounter a greater? For how can the exchange of two kinds of knowledge ever become false opinion? As well might we suppose that ignorance could make a man know, or that blindness could make him see. Theaetetus suggests that in the aviary there may be flying about mock birds, or forms of ignorance, and we put forth our hands and grasp ignorance, when we are intending to grasp knowledge. But how can he who knows the forms of knowledge and the forms of ignorance imagine one to be the other? Is there some other form of knowledge which distinguishes them? and another, and another? Thus we go round and round in a circle and make no progress.

All this confusion arises out of our attempt to explain false opinion without having explained knowledge. What then is knowledge? Theaetetus repeats that knowledge is true opinion. But this seems to be refuted by the instance of orators and judges. For surely the orator cannot convey a true knowledge of crimes at which the judges were not present; he can only persuade them, and the judge may form a true opinion and truly judge. But if true opinion were knowledge they could not have judged without knowledge.

Once more. Theaetetus offers a definition which he has heard: Knowledge is true opinion accompanied by definition or explanation. Socrates has had a similar dream, and has further heard that the first elements are names only, and that definition or explanation begins when they are combined; the letters are unknown, the syllables or combinations are known. But this new hypothesis when tested by the letters of the alphabet is found to break down. The first syllable of Socrates' name is SO. But what is SO? Two letters, S and O, a sibilant and a vowel, of which no further explanation can be given. And how can any one be ignorant of either of them, and yet know both of them? There is, however, another alternative:—We may suppose that the syllable has a separate form or idea distinct from the letters or parts. The all of the parts may not be the whole. Theaetetus is very much inclined to adopt this suggestion, but when interrogated by Socrates he is unable to draw any distinction between the whole and all the parts. And if the syllables have no parts, then they are those original elements of which there is no explanation. But how can the syllable be known if the letter remains unknown? In learning to read as children, we are first taught the letters and then the syllables. And in music, the notes, which are the letters, have a much more distinct meaning to us than the combination of them.

Once more, then, we must ask the meaning of the statement, that 'Knowledge is right opinion, accompanied by explanation or definition.' Explanation may mean, (1) the reflection or expression of a man's thoughts—but every man who is not deaf and dumb is able to express his thoughts—or (2) the enumeration of the elements of which anything is composed. A man may have a true opinion about a waggon, but then, and then only, has he knowledge of a waggon when he is able to enumerate the hundred planks of Hesiod. Or he may know the syllables of the name Theaetetus, but not the letters; yet not until he knows both can he be said to have knowledge as well as opinion. But on the other hand he may know the syllable 'The' in the name Theaetetus, yet he may be mistaken about the same syllable in the name Theodorus, and in learning to read we often make such mistakes. And even if he could write out all the letters and syllables of your name in order, still he would only have right opinion. Yet there may be a third meaning of the definition, besides the image or expression of the mind, and the enumeration of the elements, viz. (3) perception of difference.

For example, I may see a man who has eyes, nose, and mouth;—that will not distinguish him from any other man. Or he may have a snub-nose and prominent eyes;—that will not distinguish him from myself and you and others who are like me. But when I see a certain kind of snub-nosedness, then I recognize Theaetetus. And having this sign of difference, I have knowledge. But have I knowledge or opinion of this difference; if I have only opinion I have not knowledge; if I have knowledge we assume a disputed term; for knowledge will have to be defined as right opinion with knowledge of difference.

And so, Theaetetus, knowledge is neither perception nor true opinion, nor yet definition accompanying true opinion. And I have shown that the children of your brain are not worth rearing. Are you still in labour, or have you brought all you have to say about knowledge to the birth? If you have any more thoughts, you will be the better for having got rid of these; or if you have none, you will be the better for not fancying that you know what you do not know. Observe the limits of my art, which, like my mother's, is an art of midwifery; I do not pretend to compare with the good and wise of this and other ages.

And now I go to meet Meletus at the porch of the King Archon; but to-morrow I shall hope to see you again, Theodorus, at this place.

...

I. The saying of Theaetetus, that 'Knowledge is sensible perception,' may be assumed to be a current philosophical opinion of the age. 'The ancients,' as Aristotle (De Anim.) says, citing a verse of Empedocles, 'affirmed knowledge to be the same as perception.' We may now examine these words, first, with reference to their place in the history of philosophy, and secondly, in relation to modern speculations.

(a) In the age of Socrates the mind was passing from the object to the subject. The same impulse which a century before had led men to form conceptions of the world, now led them to frame general notions of the human faculties and feelings, such as memory, opinion, and the like. The simplest of these is sensation, or sensible perception, by which Plato seems to mean the generalized notion of feelings and impressions of sense, without determining whether they are conscious or not.

The theory that 'Knowledge is sensible perception' is the antithesis of that which derives knowledge from the mind (Theaet.), or which assumes the existence of ideas independent of the mind (Parm.). Yet from their extreme abstraction these theories do not represent the opposite poles of thought in the same way that the corresponding differences would in modern philosophy. The most ideal and the most sensational have a tendency to pass into one another; Heracleitus, like his great successor Hegel, has both aspects. The Eleatic isolation of Being and the Megarian or Cynic isolation of individuals are placed in the same class by Plato (Soph.); and the same principle which is the symbol of motion to one mind is the symbol of rest to another. The Atomists, who are sometimes regarded as the Materialists of Plato, denied the reality of sensation. And in the ancient as well as the modern world there were reactions from theory to experience, from ideas to sense. This is a point of view from which the philosophy of sensation presented great attraction to the ancient thinker. Amid the conflict of ideas and the variety of opinions, the impression of sense remained certain and uniform. Hardness, softness, cold, heat, etc. are not absolutely the same to different persons, but the art of measuring could at any rate reduce them all to definite natures (Republic). Thus the doctrine that knowledge is perception supplies or seems to supply a firm standing ground. Like the other notions of the earlier Greek philosophy, it was held in a very simple way, without much basis of reasoning, and without suggesting the questions which naturally arise in our own minds on the same subject.

(b) The fixedness of impressions of sense furnishes a link of connexion between ancient and modern philosophy. The modern thinker often repeats the parallel axiom, 'All knowledge is experience.' He means to say that the outward and not the inward is both the original source and the final criterion of truth, because the outward can be observed and analyzed; the inward is only known by external results, and is dimly perceived by each man for himself. In what does this differ from the saying of Theaetetus? Chiefly in this—that the modern term 'experience,' while implying a point of departure in sense and a return to sense, also includes all the processes of reasoning and imagination which have intervened. The necessary connexion between them by no means affords a measure of the relative degree of importance which is to be ascribed to either element. For the inductive portion of any science may be small, as in mathematics or ethics, compared with that which the mind has attained by reasoning and reflection on a very few facts.

II. The saying that 'All knowledge is sensation' is identified by Plato with the Protagorean thesis that 'Man is the measure of all things.' The interpretation which Protagoras himself is supposed to give of these latter words is: 'Things are to me as they appear to me, and to you as they appear to you.' But there remains still an ambiguity both in the text and in the explanation, which has to be cleared up. Did Protagoras merely mean to assert the relativity of knowledge to the human mind? Or did he mean to deny that there is an objective standard of truth?

These two questions have not been always clearly distinguished; the relativity of knowledge has been sometimes confounded with uncertainty. The untutored mind is apt to suppose that objects exist independently of the human faculties, because they really exist independently of the faculties of any individual. In the same way, knowledge appears to be a body of truths stored up in books, which when once ascertained are independent of the discoverer. Further consideration shows us that these truths are not really independent of the mind; there is an adaptation of one to the other, of the eye to the object of sense, of the mind to the conception. There would be no world, if there neither were nor ever had been any one to perceive the world. A slight effort of reflection enables us to understand this; but no effort of reflection will enable us to pass beyond the limits of our own faculties, or to imagine the relation or adaptation of objects to the mind to be different from that of which we have experience. There are certain laws of language and logic to which we are compelled to conform, and to which our ideas naturally adapt themselves; and we can no more get rid of them than we can cease to be ourselves. The absolute and infinite, whether explained as self-existence, or as the totality of human thought, or as the Divine nature, if known to us at all, cannot escape from the category of relation.

But because knowledge is subjective or relative to the mind, we are not to suppose that we are therefore deprived of any of the tests or criteria of truth. One man still remains wiser than another, a more accurate observer and relater of facts, a truer measure of the proportions of knowledge. The nature of testimony is not altered, nor the verification of causes by prescribed methods less certain. Again, the truth must often come to a man through others, according to the measure of his capacity and education. But neither does this affect the testimony, whether written or oral, which he knows by experience to be trustworthy. He cannot escape from the laws of his own mind; and he cannot escape from the further accident of being dependent for his knowledge on others. But still this is no reason why he should always be in doubt; of many personal, of many historical and scientific facts he may be absolutely assured. And having such a mass of acknowledged truth in the mathematical and physical, not to speak of the moral sciences, the moderns have certainly no reason to acquiesce in the statement that truth is appearance only, or that there is no difference between appearance and truth.

The relativity of knowledge is a truism to us, but was a great psychological discovery in the fifth century before Christ. Of this discovery, the first distinct assertion is contained in the thesis of Protagoras. Probably he had no intention either of denying or affirming an objective standard of truth. He did not consider whether man in the higher or man in the lower sense was a 'measure of all things.' Like other great thinkers, he was absorbed with one idea, and that idea was the absoluteness of perception. Like Socrates, he seemed to see that philosophy must be brought back from 'nature' to 'truth,' from the world to man. But he did not stop to analyze whether he meant 'man' in the concrete or man in the abstract, any man or some men, 'quod semper quod ubique' or individual private judgment. Such an analysis lay beyond his sphere of thought; the age before Socrates had not arrived at these distinctions. Like the Cynics, again, he discarded knowledge in any higher sense than perception. For 'truer' or 'wiser' he substituted the word 'better,' and is not unwilling to admit that both states and individuals are capable of practical improvement. But this improvement does not arise from intellectual enlightenment, nor yet from the exertion of the will, but from a change of circumstances and impressions; and he who can effect this change in himself or others may be deemed a philosopher. In the mode of effecting it, while agreeing with Socrates and the Cynics in the importance which he attaches to practical life, he is at variance with both of them. To suppose that practice can be divorced from speculation, or that we may do good without caring about truth, is by no means singular, either in philosophy or life. The singularity of this, as of some other (so-called) sophistical doctrines, is the frankness with which they are avowed, instead of being veiled, as in modern times, under ambiguous and convenient phrases.

Plato appears to treat Protagoras much as he himself is treated by Aristotle; that is to say, he does not attempt to understand him from his own point of view. But he entangles him in the meshes of a more advanced logic. To which Protagoras is supposed to reply by Megarian quibbles, which destroy logic, 'Not only man, but each man, and each man at each moment.' In the arguments about sight and memory there is a palpable unfairness which is worthy of the great 'brainless brothers,' Euthydemus and Dionysodorus, and may be compared with the egkekalummenos ('obvelatus') of Eubulides. For he who sees with one eye only cannot be truly said both to see and not to see; nor is memory, which is liable to forget, the immediate knowledge to which Protagoras applies the term. Theodorus justly charges Socrates with going beyond the truth; and Protagoras has equally right on his side when he protests against Socrates arguing from the common use of words, which 'the vulgar pervert in all manner of ways.'

III. The theory of Protagoras is connected by Aristotle as well as Plato with the flux of Heracleitus. But Aristotle is only following Plato, and Plato, as we have already seen, did not mean to imply that such a connexion was admitted by Protagoras himself. His metaphysical genius saw or seemed to see a common tendency in them, just as the modern historian of ancient philosophy might perceive a parallelism between two thinkers of which they were probably unconscious themselves. We must remember throughout that Plato is not speaking of Heracleitus, but of the Heracliteans, who succeeded him; nor of the great original ideas of the master, but of the Eristic into which they had degenerated a hundred years later. There is nothing in the fragments of Heracleitus which at all justifies Plato's account of him. His philosophy may be resolved into two elements—first, change, secondly, law or measure pervading the change: these he saw everywhere, and often expressed in strange mythological symbols. But he has no analysis of sensible perception such as Plato attributes to him; nor is there any reason to suppose that he pushed his philosophy into that absolute negation in which Heracliteanism was sunk in the age of Plato. He never said that 'change means every sort of change;' and he expressly distinguished between 'the general and particular understanding.' Like a poet, he surveyed the elements of mythology, nature, thought, which lay before him, and sometimes by the light of genius he saw or seemed to see a mysterious principle working behind them. But as has been the case with other great philosophers, and with Plato and Aristotle themselves, what was really permanent and original could not be understood by the next generation, while a perverted logic carried out his chance expressions with an illogical consistency. His simple and noble thoughts, like those of the great Eleatic, soon degenerated into a mere strife of words. And when thus reduced to mere words, they seem to have exercised a far wider influence in the cities of Ionia (where the people 'were mad about them') than in the life-time of Heracleitus—a phenomenon which, though at first sight singular, is not without a parallel in the history of philosophy and theology.

It is this perverted form of the Heraclitean philosophy which is supposed to effect the final overthrow of Protagorean sensationalism. For if all things are changing at every moment, in all sorts of ways, then there is nothing fixed or defined at all, and therefore no sensible perception, nor any true word by which that or anything else can be described. Of course Protagoras would not have admitted the justice of this argument any more than Heracleitus would have acknowledged the 'uneducated fanatics' who appealed to his writings. He might have said, 'The excellent Socrates has first confused me with Heracleitus, and Heracleitus with his Ephesian successors, and has then disproved the existence both of knowledge and sensation. But I am not responsible for what I never said, nor will I admit that my common-sense account of knowledge can be overthrown by unintelligible Heraclitean paradoxes.'

IV. Still at the bottom of the arguments there remains a truth, that knowledge is something more than sensible perception;—this alone would not distinguish man from a tadpole. The absoluteness of sensations at each moment destroys the very consciousness of sensations (compare Phileb.), or the power of comparing them. The senses are not mere holes in a 'Trojan horse,' but the organs of a presiding nature, in which they meet. A great advance has been made in psychology when the senses are recognized as organs of sense, and we are admitted to see or feel 'through them' and not 'by them,' a distinction of words which, as Socrates observes, is by no means pedantic. A still further step has been made when the most abstract notions, such as Being and Not-being, sameness and difference, unity and plurality, are acknowledged to be the creations of the mind herself, working upon the feelings or impressions of sense. In this manner Plato describes the process of acquiring them, in the words 'Knowledge consists not in the feelings or affections (pathemasi), but in the process of reasoning about them (sullogismo).' Here, is in the Parmenides, he means something not really different from generalization. As in the Sophist, he is laying the foundation of a rational psychology, which is to supersede the Platonic reminiscence of Ideas as well as the Eleatic Being and the individualism of Megarians and Cynics.

V. Having rejected the doctrine that 'Knowledge is perception,' we now proceed to look for a definition of knowledge in the sphere of opinion. But here we are met by a singular difficulty: How is false opinion possible? For we must either know or not know that which is presented to the mind or to sense. We of course should answer at once: 'No; the alternative is not necessary, for there may be degrees of knowledge; and we may know and have forgotten, or we may be learning, or we may have a general but not a particular knowledge, or we may know but not be able to explain;' and many other ways may be imagined in which we know and do not know at the same time. But these answers belong to a later stage of metaphysical discussion; whereas the difficulty in question naturally arises owing to the childhood of the human mind, like the parallel difficulty respecting Not-being. Men had only recently arrived at the notion of opinion; they could not at once define the true and pass beyond into the false. The very word doxa was full of ambiguity, being sometimes, as in the Eleatic philosophy, applied to the sensible world, and again used in the more ordinary sense of opinion. There is no connexion between sensible appearance and probability, and yet both of them met in the word doxa, and could hardly be disengaged from one another in the mind of the Greek living in the fifth or fourth century B.C. To this was often added, as at the end of the fifth book of the Republic, the idea of relation, which is equally distinct from either of them; also a fourth notion, the conclusion of the dialectical process, the making up of the mind after she has been 'talking to herself' (Theat.).

We are not then surprised that the sphere of opinion and of Not-being should be a dusky, half-lighted place (Republic), belonging neither to the old world of sense and imagination, nor to the new world of reflection and reason. Plato attempts to clear up this darkness. In his accustomed manner he passes from the lower to the higher, without omitting the intermediate stages. This appears to be the reason why he seeks for the definition of knowledge first in the sphere of opinion. Hereafter we shall find that something more than opinion is required.

False opinion is explained by Plato at first as a confusion of mind and sense, which arises when the impression on the mind does not correspond to the impression made on the senses. It is obvious that this explanation (supposing the distinction between impressions on the mind and impressions on the senses to be admitted) does not account for all forms of error; and Plato has excluded himself from the consideration of the greater number, by designedly omitting the intermediate processes of learning and forgetting; nor does he include fallacies in the use of language or erroneous inferences. But he is struck by one possibility of error, which is not covered by his theory, viz. errors in arithmetic. For in numbers and calculation there is no combination of thought and sense, and yet errors may often happen. Hence he is led to discard the explanation which might nevertheless have been supposed to hold good (for anything which he says to the contrary) as a rationale of error, in the case of facts derived from sense.

Another attempt is made to explain false opinion by assigning to error a sort of positive existence. But error or ignorance is essentially negative—a not-knowing; if we knew an error, we should be no longer in error. We may veil our difficulty under figures of speech, but these, although telling arguments with the multitude, can never be the real foundation of a system of psychology. Only they lead us to dwell upon mental phenomena which if expressed in an abstract form would not be realized by us at all. The figure of the mind receiving impressions is one of those images which have rooted themselves for ever in language. It may or may not be a 'gracious aid' to thought; but it cannot be got rid of. The other figure of the enclosure is also remarkable as affording the first hint of universal all-pervading ideas,—a notion further carried out in the Sophist. This is implied in the birds, some in flocks, some solitary, which fly about anywhere and everywhere. Plato discards both figures, as not really solving the question which to us appears so simple: 'How do we make mistakes?' The failure of the enquiry seems to show that we should return to knowledge, and begin with that; and we may afterwards proceed, with a better hope of success, to the examination of opinion.

But is true opinion really distinct from knowledge? The difference between these he seeks to establish by an argument, which to us appears singular and unsatisfactory. The existence of true opinion is proved by the rhetoric of the law courts, which cannot give knowledge, but may give true opinion. The rhetorician cannot put the judge or juror in possession of all the facts which prove an act of violence, but he may truly persuade them of the commission of such an act. Here the idea of true opinion seems to be a right conclusion from imperfect knowledge. But the correctness of such an opinion will be purely accidental; and is really the effect of one man, who has the means of knowing, persuading another who has not. Plato would have done better if he had said that true opinion was a contradiction in terms.

Assuming the distinction between knowledge and opinion, Theaetetus, in answer to Socrates, proceeds to define knowledge as true opinion, with definite or rational explanation. This Socrates identifies with another and different theory, of those who assert that knowledge first begins with a proposition.

The elements may be perceived by sense, but they are names, and cannot be defined. When we assign to them some predicate, they first begin to have a meaning (onomaton sumploke logou ousia). This seems equivalent to saying, that the individuals of sense become the subject of knowledge when they are regarded as they are in nature in relation to other individuals.

Yet we feel a difficulty in following this new hypothesis. For must not opinion be equally expressed in a proposition? The difference between true and false opinion is not the difference between the particular and the universal, but between the true universal and the false. Thought may be as much at fault as sight. When we place individuals under a class, or assign to them attributes, this is not knowledge, but a very rudimentary process of thought; the first generalization of all, without which language would be impossible. And has Plato kept altogether clear of a confusion, which the analogous word logos tends to create, of a proposition and a definition? And is not the confusion increased by the use of the analogous term 'elements,' or 'letters'? For there is no real resemblance between the relation of letters to a syllable, and of the terms to a proposition.

Plato, in the spirit of the Megarian philosophy, soon discovers a flaw in the explanation. For how can we know a compound of which the simple elements are unknown to us? Can two unknowns make a known? Can a whole be something different from the parts? The answer of experience is that they can; for we may know a compound, which we are unable to analyze into its elements; and all the parts, when united, may be more than all the parts separated: e.g. the number four, or any other number, is more than the units which are contained in it; any chemical compound is more than and different from the simple elements. But ancient philosophy in this, as in many other instances, proceeding by the path of mental analysis, was perplexed by doubts which warred against the plainest facts.

Three attempts to explain the new definition of knowledge still remain to be considered. They all of them turn on the explanation of logos. The first account of the meaning of the word is the reflection of thought in speech—a sort of nominalism 'La science est une langue bien faite.' But anybody who is not dumb can say what he thinks; therefore mere speech cannot be knowledge. And yet we may observe, that there is in this explanation an element of truth which is not recognized by Plato; viz. that truth and thought are inseparable from language, although mere expression in words is not truth. The second explanation of logos is the enumeration of the elementary parts of the complex whole. But this is only definition accompanied with right opinion, and does not yet attain to the certainty of knowledge. Plato does not mention the greater objection, which is, that the enumeration of particulars is endless; such a definition would be based on no principle, and would not help us at all in gaining a common idea. The third is the best explanation,—the possession of a characteristic mark, which seems to answer to the logical definition by genus and difference. But this, again, is equally necessary for right opinion; and we have already determined, although not on very satisfactory grounds, that knowledge must be distinguished from opinion. A better distinction is drawn between them in the Timaeus. They might be opposed as philosophy and rhetoric, and as conversant respectively with necessary and contingent matter. But no true idea of the nature of either of them, or of their relation to one another, could be framed until science obtained a content. The ancient philosophers in the age of Plato thought of science only as pure abstraction, and to this opinion stood in no relation.

Like Theaetetus, we have attained to no definite result. But an interesting phase of ancient philosophy has passed before us. And the negative result is not to be despised. For on certain subjects, and in certain states of knowledge, the work of negation or clearing the ground must go on, perhaps for a generation, before the new structure can begin to rise. Plato saw the necessity of combating the illogical logic of the Megarians and Eristics. For the completion of the edifice, he makes preparation in the Theaetetus, and crowns the work in the Sophist.

Many (1) fine expressions, and (2) remarks full of wisdom, (3) also germs of a metaphysic of the future, are scattered up and down in the dialogue. Such, for example, as (1) the comparison of Theaetetus' progress in learning to the 'noiseless flow of a river of oil'; the satirical touch, 'flavouring a sauce or fawning speech'; or the remarkable expression, 'full of impure dialectic'; or the lively images under which the argument is described,—'the flood of arguments pouring in,' the fresh discussions 'bursting in like a band of revellers.' (2) As illustrations of the second head, may be cited the remark of Socrates, that 'distinctions of words, although sometimes pedantic, are also necessary'; or the fine touch in the character of the lawyer, that 'dangers came upon him when the tenderness of youth was unequal to them'; or the description of the manner in which the spirit is broken in a wicked man who listens to reproof until he becomes like a child; or the punishment of the wicked, which is not physical suffering, but the perpetual companionship of evil (compare Gorgias); or the saying, often repeated by Aristotle and others, that 'philosophy begins in wonder, for Iris is the child of Thaumas'; or the superb contempt with which the philosopher takes down the pride of wealthy landed proprietors by comparison of the whole earth. (3) Important metaphysical ideas are: a. the conception of thought, as the mind talking to herself; b. the notion of a common sense, developed further by Aristotle, and the explicit declaration, that the mind gains her conceptions of Being, sameness, number, and the like, from reflection on herself; c. the excellent distinction of Theaetetus (which Socrates, speaking with emphasis, 'leaves to grow') between seeing the forms or hearing the sounds of words in a foreign language, and understanding the meaning of them; and d. the distinction of Socrates himself between 'having' and 'possessing' knowledge, in which the answer to the whole discussion appears to be contained.

...

There is a difference between ancient and modern psychology, and we have a difficulty in explaining one in the terms of the other. To us the inward and outward sense and the inward and outward worlds of which they are the organs are parted by a wall, and appear as if they could never be confounded. The mind is endued with faculties, habits, instincts, and a personality or consciousness in which they are bound together. Over against these are placed forms, colours, external bodies coming into contact with our own body. We speak of a subject which is ourselves, of an object which is all the rest. These are separable in thought, but united in any act of sensation, reflection, or volition. As there are various degrees in which the mind may enter into or be abstracted from the operations of sense, so there are various points at which this separation or union may be supposed to occur. And within the sphere of mind the analogy of sense reappears; and we distinguish not only external objects, but objects of will and of knowledge which we contrast with them. These again are comprehended in a higher object, which reunites with the subject. A multitude of abstractions are created by the efforts of successive thinkers which become logical determinations; and they have to be arranged in order, before the scheme of thought is complete. The framework of the human intellect is not the peculium of an individual, but the joint work of many who are of all ages and countries. What we are in mind is due, not merely to our physical, but to our mental antecedents which we trace in history, and more especially in the history of philosophy. Nor can mental phenomena be truly explained either by physiology or by the observation of consciousness apart from their history. They have a growth of their own, like the growth of a flower, a tree, a human being. They may be conceived as of themselves constituting a common mind, and having a sort of personal identity in which they coexist.

So comprehensive is modern psychology, seeming to aim at constructing anew the entire world of thought. And prior to or simultaneously with this construction a negative process has to be carried on, a clearing away of useless abstractions which we have inherited from the past. Many erroneous conceptions of the mind derived from former philosophies have found their way into language, and we with difficulty disengage ourselves from them. Mere figures of speech have unconsciously influenced the minds of great thinkers. Also there are some distinctions, as, for example, that of the will and of the reason, and of the moral and intellectual faculties, which are carried further than is justified by experience. Any separation of things which we cannot see or exactly define, though it may be necessary, is a fertile source of error. The division of the mind into faculties or powers or virtues is too deeply rooted in language to be got rid of, but it gives a false impression. For if we reflect on ourselves we see that all our faculties easily pass into one another, and are bound together in a single mind or consciousness; but this mental unity is apt to be concealed from us by the distinctions of language.

A profusion of words and ideas has obscured rather than enlightened mental science. It is hard to say how many fallacies have arisen from the representation of the mind as a box, as a 'tabula rasa,' a book, a mirror, and the like. It is remarkable how Plato in the Theaetetus, after having indulged in the figure of the waxen tablet and the decoy, afterwards discards them. The mind is also represented by another class of images, as the spring of a watch, a motive power, a breath, a stream, a succession of points or moments. As Plato remarks in the Cratylus, words expressive of motion as well as of rest are employed to describe the faculties and operations of the mind; and in these there is contained another store of fallacies. Some shadow or reflection of the body seems always to adhere to our thoughts about ourselves, and mental processes are hardly distinguished in language from bodily ones. To see or perceive are used indifferently of both; the words intuition, moral sense, common sense, the mind's eye, are figures of speech transferred from one to the other. And many other words used in early poetry or in sacred writings to express the works of mind have a materialistic sound; for old mythology was allied to sense, and the distinction of matter and mind had not as yet arisen. Thus materialism receives an illusive aid from language; and both in philosophy and religion the imaginary figure or association easily takes the place of real knowledge.

Again, there is the illusion of looking into our own minds as if our thoughts or feelings were written down in a book. This is another figure of speech, which might be appropriately termed 'the fallacy of the looking-glass.' We cannot look at the mind unless we have the eye which sees, and we can only look, not into, but out of the mind at the thoughts, words, actions of ourselves and others. What we dimly recognize within us is not experience, but rather the suggestion of an experience, which we may gather, if we will, from the observation of the world. The memory has but a feeble recollection of what we were saying or doing a few weeks or a few months ago, and still less of what we were thinking or feeling. This is one among many reasons why there is so little self-knowledge among mankind; they do not carry with them the thought of what they are or have been. The so-called 'facts of consciousness' are equally evanescent; they are facts which nobody ever saw, and which can neither be defined nor described. Of the three laws of thought the first (All A = A) is an identical proposition—that is to say, a mere word or symbol claiming to be a proposition: the two others (Nothing can be A and not A, and Everything is either A or not A) are untrue, because they exclude degrees and also the mixed modes and double aspects under which truth is so often presented to us. To assert that man is man is unmeaning; to say that he is free or necessary and cannot be both is a half truth only. These are a few of the entanglements which impede the natural course of human thought. Lastly, there is the fallacy which lies still deeper, of regarding the individual mind apart from the universal, or either, as a self-existent entity apart from the ideas which are contained in them.

In ancient philosophies the analysis of the mind is still rudimentary and imperfect. It naturally began with an effort to disengage the universal from sense—this was the first lifting up of the mist. It wavered between object and subject, passing imperceptibly from one or Being to mind and thought. Appearance in the outward object was for a time indistinguishable from opinion in the subject. At length mankind spoke of knowing as well as of opining or perceiving. But when the word 'knowledge' was found how was it to be explained or defined? It was not an error, it was a step in the right direction, when Protagoras said that 'Man is the measure of all things,' and that 'All knowledge is perception.' This was the subjective which corresponded to the objective 'All is flux.' But the thoughts of men deepened, and soon they began to be aware that knowledge was neither sense, nor yet opinion—with or without explanation; nor the expression of thought, nor the enumeration of parts, nor the addition of characteristic marks. Motion and rest were equally ill adapted to express its nature, although both must in some sense be attributed to it; it might be described more truly as the mind conversing with herself; the discourse of reason; the hymn of dialectic, the science of relations, of ideas, of the so-called arts and sciences, of the one, of the good, of the all:—this is the way along which Plato is leading us in his later dialogues. In its higher signification it was the knowledge, not of men, but of gods, perfect and all sufficing:—like other ideals always passing out of sight, and nevertheless present to the mind of Aristotle as well as Plato, and the reality to which they were both tending. For Aristotle as well as Plato would in modern phraseology have been termed a mystic; and like him would have defined the higher philosophy to be 'Knowledge of being or essence,'—words to which in our own day we have a difficulty in attaching a meaning.

Yet, in spite of Plato and his followers, mankind have again and again returned to a sensational philosophy. As to some of the early thinkers, amid the fleetings of sensible objects, ideas alone seemed to be fixed, so to a later generation amid the fluctuation of philosophical opinions the only fixed points appeared to be outward objects. Any pretence of knowledge which went beyond them implied logical processes, of the correctness of which they had no assurance and which at best were only probable. The mind, tired of wandering, sought to rest on firm ground; when the idols of philosophy and language were stripped off, the perception of outward objects alone remained. The ancient Epicureans never asked whether the comparison of these with one another did not involve principles of another kind which were above and beyond them. In like manner the modern inductive philosophy forgot to enquire into the meaning of experience, and did not attempt to form a conception of outward objects apart from the mind, or of the mind apart from them. Soon objects of sense were merged in sensations and feelings, but feelings and sensations were still unanalyzed. At last we return to the doctrine attributed by Plato to Protagoras, that the mind is only a succession of momentary perceptions. At this point the modern philosophy of experience forms an alliance with ancient scepticism.

The higher truths of philosophy and religion are very far removed from sense. Admitting that, like all other knowledge, they are derived from experience, and that experience is ultimately resolvable into facts which come to us through the eye and ear, still their origin is a mere accident which has nothing to do with their true nature. They are universal and unseen; they belong to all times—past, present, and future. Any worthy notion of mind or reason includes them. The proof of them is, 1st, their comprehensiveness and consistency with one another; 2ndly, their agreement with history and experience. But sensation is of the present only, is isolated, is and is not in successive moments. It takes the passing hour as it comes, following the lead of the eye or ear instead of the command of reason. It is a faculty which man has in common with the animals, and in which he is inferior to many of them. The importance of the senses in us is that they are the apertures of the mind, doors and windows through which we take in and make our own the materials of knowledge. Regarded in any other point of view sensation is of all mental acts the most trivial and superficial. Hence the term 'sensational' is rightly used to express what is shallow in thought and feeling.

We propose in what follows, first of all, like Plato in the Theaetetus, to analyse sensation, and secondly to trace the connexion between theories of sensation and a sensational or Epicurean philosophy.

Paragraph I. We, as well as the ancients, speak of the five senses, and of a sense, or common sense, which is the abstraction of them. The term 'sense' is also used metaphorically, both in ancient and modern philosophy, to express the operations of the mind which are immediate or intuitive. Of the five senses, two—the sight and the hearing—are of a more subtle and complex nature, while two others—the smell and the taste—seem to be only more refined varieties of touch. All of them are passive, and by this are distinguished from the active faculty of speech: they receive impressions, but do not produce them, except in so far as they are objects of sense themselves.

Physiology speaks to us of the wonderful apparatus of nerves, muscles, tissues, by which the senses are enabled to fulfil their functions. It traces the connexion, though imperfectly, of the bodily organs with the operations of the mind. Of these latter, it seems rather to know the conditions than the causes. It can prove to us that without the brain we cannot think, and that without the eye we cannot see: and yet there is far more in thinking and seeing than is given by the brain and the eye. It observes the 'concomitant variations' of body and mind. Psychology, on the other hand, treats of the same subject regarded from another point of view. It speaks of the relation of the senses to one another; it shows how they meet the mind; it analyzes the transition from sense to thought. The one describes their nature as apparent to the outward eye; by the other they are regarded only as the instruments of the mind. It is in this latter point of view that we propose to consider them.

The simplest sensation involves an unconscious or nascent operation of the mind; it implies objects of sense, and objects of sense have differences of form, number, colour. But the conception of an object without us, or the power of discriminating numbers, forms, colours, is not given by the sense, but by the mind. A mere sensation does not attain to distinctness: it is a confused impression, sugkechumenon ti, as Plato says (Republic), until number introduces light and order into the confusion. At what point confusion becomes distinctness is a question of degree which cannot be precisely determined. The distant object, the undefined notion, come out into relief as we approach them or attend to them. Or we may assist the analysis by attempting to imagine the world first dawning upon the eye of the infant or of a person newly restored to sight. Yet even with them the mind as well as the eye opens or enlarges. For all three are inseparably bound together—the object would be nowhere and nothing, if not perceived by the sense, and the sense would have no power of distinguishing without the mind.

But prior to objects of sense there is a third nature in which they are contained—that is to say, space, which may be explained in various ways. It is the element which surrounds them; it is the vacuum or void which they leave or occupy when passing from one portion of space to another. It might be described in the language of ancient philosophy, as 'the Not-being' of objects. It is a negative idea which in the course of ages has become positive. It is originally derived from the contemplation of the world without us—the boundless earth or sea, the vacant heaven, and is therefore acquired chiefly through the sense of sight: to the blind the conception of space is feeble and inadequate, derived for the most part from touch or from the descriptions of others. At first it appears to be continuous; afterwards we perceive it to be capable of division by lines or points, real or imaginary. By the help of mathematics we form another idea of space, which is altogether independent of experience. Geometry teaches us that the innumerable lines and figures by which space is or may be intersected are absolutely true in all their combinations and consequences. New and unchangeable properties of space are thus developed, which are proved to us in a thousand ways by mathematical reasoning as well as by common experience. Through quantity and measure we are conducted to our simplest and purest notion of matter, which is to the cube or solid what space is to the square or surface. And all our applications of mathematics are applications of our ideas of space to matter. No wonder then that they seem to have a necessary existence to us. Being the simplest of our ideas, space is also the one of which we have the most difficulty in ridding ourselves. Neither can we set a limit to it, for wherever we fix a limit, space is springing up beyond. Neither can we conceive a smallest or indivisible portion of it; for within the smallest there is a smaller still; and even these inconceivable qualities of space, whether the infinite or the infinitesimal, may be made the subject of reasoning and have a certain truth to us.

Whether space exists in the mind or out of it, is a question which has no meaning. We should rather say that without it the mind is incapable of conceiving the body, and therefore of conceiving itself. The mind may be indeed imagined to contain the body, in the same way that Aristotle (partly following Plato) supposes God to be the outer heaven or circle of the universe. But how can the individual mind carry about the universe of space packed up within, or how can separate minds have either a universe of their own or a common universe? In such conceptions there seems to be a confusion of the individual and the universal. To say that we can only have a true idea of ourselves when we deny the reality of that by which we have any idea of ourselves is an absurdity. The earth which is our habitation and 'the starry heaven above' and we ourselves are equally an illusion, if space is only a quality or condition of our minds.

Again, we may compare the truths of space with other truths derived from experience, which seem to have a necessity to us in proportion to the frequency of their recurrence or the truth of the consequences which may be inferred from them. We are thus led to remark that the necessity in our ideas of space on which much stress has been laid, differs in a slight degree only from the necessity which appears to belong to other of our ideas, e.g. weight, motion, and the like. And there is another way in which this necessity may be explained. We have been taught it, and the truth which we were taught or which we inherited has never been contradicted in all our experience and is therefore confirmed by it. Who can resist an idea which is presented to him in a general form in every moment of his life and of which he finds no instance to the contrary? The greater part of what is sometimes regarded as the a priori intuition of space is really the conception of the various geometrical figures of which the properties have been revealed by mathematical analysis. And the certainty of these properties is immeasurably increased to us by our finding that they hold good not only in every instance, but in all the consequences which are supposed to flow from them.

Neither must we forget that our idea of space, like our other ideas, has a history. The Homeric poems contain no word for it; even the later Greek philosophy has not the Kantian notion of space, but only the definite 'place' or 'the infinite.' To Plato, in the Timaeus, it is known only as the 'nurse of generation.' When therefore we speak of the necessity of our ideas of space we must remember that this is a necessity which has grown up with the growth of the human mind, and has been made by ourselves. We can free ourselves from the perplexities which are involved in it by ascending to a time in which they did not as yet exist. And when space or time are described as 'a priori forms or intuitions added to the matter given in sensation,' we should consider that such expressions belong really to the 'pre-historic study' of philosophy, i.e. to the eighteenth century, when men sought to explain the human mind without regard to history or language or the social nature of man.

In every act of sense there is a latent perception of space, of which we only become conscious when objects are withdrawn from it. There are various ways in which we may trace the connexion between them. We may think of space as unresisting matter, and of matter as divided into objects; or of objects again as formed by abstraction into a collective notion of matter, and of matter as rarefied into space. And motion may be conceived as the union of there and not there in space, and force as the materializing or solidification of motion. Space again is the individual and universal in one; or, in other words, a perception and also a conception. So easily do what are sometimes called our simple ideas pass into one another, and differences of kind resolve themselves into differences of degree.

Within or behind space there is another abstraction in many respects similar to it—time, the form of the inward, as space is the form of the outward. As we cannot think of outward objects of sense or of outward sensations without space, so neither can we think of a succession of sensations without time. It is the vacancy of thoughts or sensations, as space is the void of outward objects, and we can no more imagine the mind without the one than the world without the other. It is to arithmetic what space is to geometry; or, more strictly, arithmetic may be said to be equally applicable to both. It is defined in our minds, partly by the analogy of space and partly by the recollection of events which have happened to us, or the consciousness of feelings which we are experiencing. Like space, it is without limit, for whatever beginning or end of time we fix, there is a beginning and end before them, and so on without end. We speak of a past, present, and future, and again the analogy of space assists us in conceiving of them as coexistent. When the limit of time is removed there arises in our minds the idea of eternity, which at first, like time itself, is only negative, but gradually, when connected with the world and the divine nature, like the other negative infinity of space, becomes positive. Whether time is prior to the mind and to experience, or coeval with them, is (like the parallel question about space) unmeaning. Like space it has been realized gradually: in the Homeric poems, or even in the Hesiodic cosmogony, there is no more notion of time than of space. The conception of being is more general than either, and might therefore with greater plausibility be affirmed to be a condition or quality of the mind. The a priori intuitions of Kant would have been as unintelligible to Plato as his a priori synthetical propositions to Aristotle. The philosopher of Konigsberg supposed himself to be analyzing a necessary mode of thought: he was not aware that he was dealing with a mere abstraction. But now that we are able to trace the gradual developement of ideas through religion, through language, through abstractions, why should we interpose the fiction of time between ourselves and realities? Why should we single out one of these abstractions to be the a priori condition of all the others? It comes last and not first in the order of our thoughts, and is not the condition precedent of them, but the last generalization of them. Nor can any principle be imagined more suicidal to philosophy than to assume that all the truth which we are capable of attaining is seen only through an unreal medium. If all that exists in time is illusion, we may well ask with Plato, 'What becomes of the mind?'

Leaving the a priori conditions of sensation we may proceed to consider acts of sense. These admit of various degrees of duration or intensity; they admit also of a greater or less extension from one object, which is perceived directly, to many which are perceived indirectly or in a less degree, and to the various associations of the object which are latent in the mind. In general the greater the intension the less the extension of them. The simplest sensation implies some relation of objects to one another, some position in space, some relation to a previous or subsequent sensation. The acts of seeing and hearing may be almost unconscious and may pass away unnoted; they may also leave an impression behind them or power of recalling them. If, after seeing an object we shut our eyes, the object remains dimly seen in the same or about the same place, but with form and lineaments half filled up. This is the simplest act of memory. And as we cannot see one thing without at the same time seeing another, different objects hang together in recollection, and when we call for one the other quickly follows. To think of the place in which we have last seen a thing is often the best way of recalling it to the mind. Hence memory is dependent on association. The act of recollection may be compared to the sight of an object at a great distance which we have previously seen near and seek to bring near to us in thought. Memory is to sense as dreaming is to waking; and like dreaming has a wayward and uncertain power of recalling impressions from the past.

Thus begins the passage from the outward to the inward sense. But as yet there is no conception of a universal—the mind only remembers the individual object or objects, and is always attaching to them some colour or association of sense. The power of recollection seems to depend on the intensity or largeness of the perception, or on the strength of some emotion with which it is inseparably connected. This is the natural memory which is allied to sense, such as children appear to have and barbarians and animals. It is necessarily limited in range, and its limitation is its strength. In later life, when the mind has become crowded with names, acts, feelings, images innumerable, we acquire by education another memory of system and arrangement which is both stronger and weaker than the first—weaker in the recollection of sensible impressions as they are represented to us by eye or ear—stronger by the natural connexion of ideas with objects or with one another. And many of the notions which form a part of the train of our thoughts are hardly realized by us at the time, but, like numbers or algebraical symbols, are used as signs only, thus lightening the labour of recollection.

And now we may suppose that numerous images present themselves to the mind, which begins to act upon them and to arrange them in various ways. Besides the impression of external objects present with us or just absent from us, we have a dimmer conception of other objects which have disappeared from our immediate recollection and yet continue to exist in us. The mind is full of fancies which are passing to and fro before it. Some feeling or association calls them up, and they are uttered by the lips. This is the first rudimentary imagination, which may be truly described in the language of Hobbes, as 'decaying sense,' an expression which may be applied with equal truth to memory as well. For memory and imagination, though we sometimes oppose them, are nearly allied; the difference between them seems chiefly to lie in the activity of the one compared with the passivity of the other. The sense decaying in memory receives a flash of light or life from imagination. Dreaming is a link of connexion between them; for in dreaming we feebly recollect and also feebly imagine at one and the same time. When reason is asleep the lower part of the mind wanders at will amid the images which have been received from without, the intelligent element retires, and the sensual or sensuous takes its place. And so in the first efforts of imagination reason is latent or set aside; and images, in part disorderly, but also having a unity (however imperfect) of their own, pour like a flood over the mind. And if we could penetrate into the heads of animals we should probably find that their intelligence, or the state of what in them is analogous to our intelligence, is of this nature.

Thus far we have been speaking of men, rather in the points in which they resemble animals than in the points in which they differ from them. The animal too has memory in various degrees, and the elements of imagination, if, as appears to be the case, he dreams. How far their powers or instincts are educated by the circumstances of their lives or by intercourse with one another or with mankind, we cannot precisely tell. They, like ourselves, have the physical inheritance of form, scent, hearing, sight, and other qualities or instincts. But they have not the mental inheritance of thoughts and ideas handed down by tradition, 'the slow additions that build up the mind' of the human race. And language, which is the great educator of mankind, is wanting in them; whereas in us language is ever present—even in the infant the latent power of naming is almost immediately observable. And therefore the description which has been already given of the nascent power of the faculties is in reality an anticipation. For simultaneous with their growth in man a growth of language must be supposed. The child of two years old sees the fire once and again, and the feeble observation of the same recurring object is associated with the feeble utterance of the name by which he is taught to call it. Soon he learns to utter the name when the object is no longer there, but the desire or imagination of it is present to him. At first in every use of the word there is a colour of sense, an indistinct picture of the object which accompanies it. But in later years he sees in the name only the universal or class word, and the more abstract the notion becomes, the more vacant is the image which is presented to him. Henceforward all the operations of his mind, including the perceptions of sense, are a synthesis of sensations, words, conceptions. In seeing or hearing or looking or listening the sensible impression prevails over the conception and the word. In reflection the process is reversed—the outward object fades away into nothingness, the name or the conception or both together are everything. Language, like number, is intermediate between the two, partaking of the definiteness of the outer and of the universality of the inner world. For logic teaches us that every word is really a universal, and only condescends by the help of position or circumlocution to become the expression of individuals or particulars. And sometimes by using words as symbols we are able to give a 'local habitation and a name' to the infinite and inconceivable.

Thus we see that no line can be drawn between the powers of sense and of reflection—they pass imperceptibly into one another. We may indeed distinguish between the seeing and the closed eye—between the sensation and the recollection of it. But this distinction carries us a very little way, for recollection is present in sight as well as sight in recollection. There is no impression of sense which does not simultaneously recall differences of form, number, colour, and the like. Neither is such a distinction applicable at all to our internal bodily sensations, which give no sign of themselves when unaccompanied with pain, and even when we are most conscious of them, have often no assignable place in the human frame. Who can divide the nerves or great nervous centres from the mind which uses them? Who can separate the pains and pleasures of the mind from the pains and pleasures of the body? The words 'inward and outward,' 'active and passive,' 'mind and body,' are best conceived by us as differences of degree passing into differences of kind, and at one time and under one aspect acting in harmony and then again opposed. They introduce a system and order into the knowledge of our being; and yet, like many other general terms, are often in advance of our actual analysis or observation.

According to some writers the inward sense is only the fading away or imperfect realization of the outward. But this leaves out of sight one half of the phenomenon. For the mind is not only withdrawn from the world of sense but introduced to a higher world of thought and reflection, in which, like the outward sense, she is trained and educated. By use the outward sense becomes keener and more intense, especially when confined within narrow limits. The savage with little or no thought has a quicker discernment of the track than the civilised man; in like manner the dog, having the help of scent as well as of sight, is superior to the savage. By use again the inward thought becomes more defined and distinct; what was at first an effort is made easy by the natural instrumentality of language, and the mind learns to grasp universals with no more exertion than is required for the sight of an outward object. There is a natural connexion and arrangement of them, like the association of objects in a landscape. Just as a note or two of music suffices to recall a whole piece to the musician's or composer's mind, so a great principle or leading thought suggests and arranges a world of particulars. The power of reflection is not feebler than the faculty of sense, but of a higher and more comprehensive nature. It not only receives the universals of sense, but gives them a new content by comparing and combining them with one another. It withdraws from the seen that it may dwell in the unseen. The sense only presents us with a flat and impenetrable surface: the mind takes the world to pieces and puts it together on a new pattern. The universals which are detached from sense are reconstructed in science. They and not the mere impressions of sense are the truth of the world in which we live; and (as an argument to those who will only believe 'what they can hold in their hands') we may further observe that they are the source of our power over it. To say that the outward sense is stronger than the inward is like saying that the arm of the workman is stronger than the constructing or directing mind.

Returning to the senses we may briefly consider two questions—first their relation to the mind, secondly, their relation to outward objects:—

1. The senses are not merely 'holes set in a wooden horse' (Theaet.), but instruments of the mind with which they are organically connected. There is no use of them without some use of words—some natural or latent logic—some previous experience or observation. Sensation, like all other mental processes, is complex and relative, though apparently simple. The senses mutually confirm and support one another; it is hard to say how much our impressions of hearing may be affected by those of sight, or how far our impressions of sight may be corrected by the touch, especially in infancy. The confirmation of them by one another cannot of course be given by any one of them. Many intuitions which are inseparable from the act of sense are really the result of complicated reasonings. The most cursory glance at objects enables the experienced eye to judge approximately of their relations and distance, although nothing is impressed upon the retina except colour, including gradations of light and shade. From these delicate and almost imperceptible differences we seem chiefly to derive our ideas of distance and position. By comparison of what is near with what is distant we learn that the tree, house, river, etc. which are a long way off are objects of a like nature with those which are seen by us in our immediate neighbourhood, although the actual impression made on the eye is very different in one case and in the other. This is a language of 'large and small letters' (Republic), slightly differing in form and exquisitely graduated by distance, which we are learning all our life long, and which we attain in various degrees according to our powers of sight or observation. There is nor the consideration. The greater or less strain upon the nerves of the eye or ear is communicated to the mind and silently informs the judgment. We have also the use not of one eye only, but of two, which give us a wider range, and help us to discern, by the greater or less acuteness of the angle which the rays of sight form, the distance of an object and its relation to other objects. But we are already passing beyond the limits of our actual knowledge on a subject which has given rise to many conjectures. More important than the addition of another conjecture is the observation, whether in the case of sight or of any other sense, of the great complexity of the causes and the great simplicity of the effect.

The sympathy of the mind and the ear is no less striking than the sympathy of the mind and the eye. Do we not seem to perceive instinctively and as an act of sense the differences of articulate speech and of musical notes? Yet how small a part of speech or of music is produced by the impression of the ear compared with that which is furnished by the mind!

Again: the more refined faculty of sense, as in animals so also in man, seems often to be transmitted by inheritance. Neither must we forget that in the use of the senses, as in his whole nature, man is a social being, who is always being educated by language, habit, and the teaching of other men as well as by his own observation. He knows distance because he is taught it by a more experienced judgment than his own; he distinguishes sounds because he is told to remark them by a person of a more discerning ear. And as we inherit from our parents or other ancestors peculiar powers of sense or feeling, so we improve and strengthen them, not only by regular teaching, but also by sympathy and communion with other persons.

2. The second question, namely, that concerning the relation of the mind to external objects, is really a trifling one, though it has been made the subject of a famous philosophy. We may if we like, with Berkeley, resolve objects of sense into sensations; but the change is one of name only, and nothing is gained and something is lost by such a resolution or confusion of them. For we have not really made a single step towards idealism, and any arbitrary inversion of our ordinary modes of speech is disturbing to the mind. The youthful metaphysician is delighted at his marvellous discovery that nothing is, and that what we see or feel is our sensation only: for a day or two the world has a new interest to him; he alone knows the secret which has been communicated to him by the philosopher, that mind is all—when in fact he is going out of his mind in the first intoxication of a great thought. But he soon finds that all things remain as they were—the laws of motion, the properties of matter, the qualities of substances. After having inflicted his theories on any one who is willing to receive them 'first on his father and mother, secondly on some other patient listener, thirdly on his dog,' he finds that he only differs from the rest of mankind in the use of a word. He had once hoped that by getting rid of the solidity of matter he might open a passage to worlds beyond. He liked to think of the world as the representation of the divine nature, and delighted to imagine angels and spirits wandering through space, present in the room in which he is sitting without coming through the door, nowhere and everywhere at the same instant. At length he finds that he has been the victim of his own fancies; he has neither more nor less evidence of the supernatural than he had before. He himself has become unsettled, but the laws of the world remain fixed as at the beginning. He has discovered that his appeal to the fallibility of sense was really an illusion. For whatever uncertainty there may be in the appearances of nature, arises only out of the imperfection or variation of the human senses, or possibly from the deficiency of certain branches of knowledge; when science is able to apply her tests, the uncertainty is at an end. We are apt sometimes to think that moral and metaphysical philosophy are lowered by the influence which is exercised over them by physical science. But any interpretation of nature by physical science is far in advance of such idealism. The philosophy of Berkeley, while giving unbounded license to the imagination, is still grovelling on the level of sense.

We may, if we please, carry this scepticism a step further, and deny, not only objects of sense, but the continuity of our sensations themselves. We may say with Protagoras and Hume that what is appears, and that what appears appears only to individuals, and to the same individual only at one instant. But then, as Plato asks,—and we must repeat the question,—What becomes of the mind? Experience tells us by a thousand proofs that our sensations of colour, taste, and the like, are the same as they were an instant ago—that the act which we are performing one minute is continued by us in the next—and also supplies abundant proof that the perceptions of other men are, speaking generally, the same or nearly the same with our own. After having slowly and laboriously in the course of ages gained a conception of a whole and parts, of the constitution of the mind, of the relation of man to God and nature, imperfect indeed, but the best we can, we are asked to return again to the 'beggarly elements' of ancient scepticism, and acknowledge only atoms and sensations devoid of life or unity. Why should we not go a step further still and doubt the existence of the senses of all things? We are but 'such stuff as dreams are made of;' for we have left ourselves no instruments of thought by which we can distinguish man from the animals, or conceive of the existence even of a mollusc. And observe, this extreme scepticism has been allowed to spring up among us, not, like the ancient scepticism, in an age when nature and language really seemed to be full of illusions, but in the eighteenth and nineteenth centuries, when men walk in the daylight of inductive science.

The attractiveness of such speculations arises out of their true nature not being perceived. They are veiled in graceful language; they are not pushed to extremes; they stop where the human mind is disposed also to stop—short of a manifest absurdity. Their inconsistency is not observed by their authors or by mankind in general, who are equally inconsistent themselves. They leave on the mind a pleasing sense of wonder and novelty: in youth they seem to have a natural affinity to one class of persons as poetry has to another; but in later life either we drift back into common sense, or we make them the starting-points of a higher philosophy.

We are often told that we should enquire into all things before we accept them;—with what limitations is this true? For we cannot use our senses without admitting that we have them, or think without presupposing that there is in us a power of thought, or affirm that all knowledge is derived from experience without implying that this first principle of knowledge is prior to experience. The truth seems to be that we begin with the natural use of the mind as of the body, and we seek to describe this as well as we can. We eat before we know the nature of digestion; we think before we know the nature of reflection. As our knowledge increases, our perception of the mind enlarges also. We cannot indeed get beyond facts, but neither can we draw any line which separates facts from ideas. And the mind is not something separate from them but included in them, and they in the mind, both having a distinctness and individuality of their own. To reduce our conception of mind to a succession of feelings and sensations is like the attempt to view a wide prospect by inches through a microscope, or to calculate a period of chronology by minutes. The mind ceases to exist when it loses its continuity, which though far from being its highest determination, is yet necessary to any conception of it. Even an inanimate nature cannot be adequately represented as an endless succession of states or conditions.

Paragraph II. Another division of the subject has yet to be considered: Why should the doctrine that knowledge is sensation, in ancient times, or of sensationalism or materialism in modern times, be allied to the lower rather than to the higher view of ethical philosophy? At first sight the nature and origin of knowledge appear to be wholly disconnected from ethics and religion, nor can we deny that the ancient Stoics were materialists, or that the materialist doctrines prevalent in modern times have been associated with great virtues, or that both religious and philosophical idealism have not unfrequently parted company with practice. Still upon the whole it must be admitted that the higher standard of duty has gone hand in hand with the higher conception of knowledge. It is Protagoras who is seeking to adapt himself to the opinions of the world; it is Plato who rises above them: the one maintaining that all knowledge is sensation; the other basing the virtues on the idea of good. The reason of this phenomenon has now to be examined.

By those who rest knowledge immediately upon sense, that explanation of human action is deemed to be the truest which is nearest to sense. As knowledge is reduced to sensation, so virtue is reduced to feeling, happiness or good to pleasure. The different virtues—the various characters which exist in the world—are the disguises of self-interest. Human nature is dried up; there is no place left for imagination, or in any higher sense for religion. Ideals of a whole, or of a state, or of a law of duty, or of a divine perfection, are out of place in an Epicurean philosophy. The very terms in which they are expressed are suspected of having no meaning. Man is to bring himself back as far as he is able to the condition of a rational beast. He is to limit himself to the pursuit of pleasure, but of this he is to make a far-sighted calculation;—he is to be rationalized, secularized, animalized: or he is to be an amiable sceptic, better than his own philosophy, and not falling below the opinions of the world.

Imagination has been called that 'busy faculty' which is always intruding upon us in the search after truth. But imagination is also that higher power by which we rise above ourselves and the commonplaces of thought and life. The philosophical imagination is another name for reason finding an expression of herself in the outward world. To deprive life of ideals is to deprive it of all higher and comprehensive aims and of the power of imparting and communicating them to others. For men are taught, not by those who are on a level with them, but by those who rise above them, who see the distant hills, who soar into the empyrean. Like a bird in a cage, the mind confined to sense is always being brought back from the higher to the lower, from the wider to the narrower view of human knowledge. It seeks to fly but cannot: instead of aspiring towards perfection, 'it hovers about this lower world and the earthly nature.' It loses the religious sense which more than any other seems to take a man out of himself. Weary of asking 'What is truth?' it accepts the 'blind witness of eyes and ears;' it draws around itself the curtain of the physical world and is satisfied. The strength of a sensational philosophy lies in the ready accommodation of it to the minds of men; many who have been metaphysicians in their youth, as they advance in years are prone to acquiesce in things as they are, or rather appear to be. They are spectators, not thinkers, and the best philosophy is that which requires of them the least amount of mental effort.

As a lower philosophy is easier to apprehend than a higher, so a lower way of life is easier to follow; and therefore such a philosophy seems to derive a support from the general practice of mankind. It appeals to principles which they all know and recognize: it gives back to them in a generalized form the results of their own experience. To the man of the world they are the quintessence of his own reflections upon life. To follow custom, to have no new ideas or opinions, not to be straining after impossibilities, to enjoy to-day with just so much forethought as is necessary to provide for the morrow, this is regarded by the greater part of the world as the natural way of passing through existence. And many who have lived thus have attained to a lower kind of happiness or equanimity. They have possessed their souls in peace without ever allowing them to wander into the region of religious or political controversy, and without any care for the higher interests of man. But nearly all the good (as well as some of the evil) which has ever been done in this world has been the work of another spirit, the work of enthusiasts and idealists, of apostles and martyrs. The leaders of mankind have not been of the gentle Epicurean type; they have personified ideas; they have sometimes also been the victims of them. But they have always been seeking after a truth or ideal of which they fell short; and have died in a manner disappointed of their hopes that they might lift the human race out of the slough in which they found them. They have done little compared with their own visions and aspirations; but they have done that little, only because they sought to do, and once perhaps thought that they were doing, a great deal more.

The philosophies of Epicurus or Hume give no adequate or dignified conception of the mind. There is no organic unity in a succession of feeling or sensations; no comprehensiveness in an infinity of separate actions. The individual never reflects upon himself as a whole; he can hardly regard one act or part of his life as the cause or effect of any other act or part. Whether in practice or speculation, he is to himself only in successive instants. To such thinkers, whether in ancient or in modern times, the mind is only the poor recipient of impressions—not the heir of all the ages, or connected with all other minds. It begins again with its own modicum of experience having only such vague conceptions of the wisdom of the past as are inseparable from language and popular opinion. It seeks to explain from the experience of the individual what can only be learned from the history of the world. It has no conception of obligation, duty, conscience—these are to the Epicurean or Utilitarian philosopher only names which interfere with our natural perceptions of pleasure and pain.

There seem then to be several answers to the question, Why the theory that all knowledge is sensation is allied to the lower rather than to the higher view of ethical philosophy:—1st, Because it is easier to understand and practise; 2ndly, Because it is fatal to the pursuit of ideals, moral, political, or religious; 3rdly, Because it deprives us of the means and instruments of higher thought, of any adequate conception of the mind, of knowledge, of conscience, of moral obligation.

...

ON THE NATURE AND LIMITS Of PSYCHOLOGY.

Since the above essay first appeared, many books on Psychology have been given to the world, partly based upon the views of Herbart and other German philosophers, partly independent of them. The subject has gained in bulk and extent; whether it has had any true growth is more doubtful. It begins to assume the language and claim the authority of a science; but it is only an hypothesis or outline, which may be filled up in many ways according to the fancy of individual thinkers. The basis of it is a precarious one,—consciousness of ourselves and a somewhat uncertain observation of the rest of mankind. Its relations to other sciences are not yet determined: they seem to be almost too complicated to be ascertained. It may be compared to an irregular building, run up hastily and not likely to last, because its foundations are weak, and in many places rest only on the surface of the ground. It has sought rather to put together scattered observations and to make them into a system than to describe or prove them. It has never severely drawn the line between facts and opinions. It has substituted a technical phraseology for the common use of language, being neither able to win acceptance for the one nor to get rid of the other.

The system which has thus arisen appears to be a kind of metaphysic narrowed to the point of view of the individual mind, through which, as through some new optical instrument limiting the sphere of vision, the interior of thought and sensation is examined. But the individual mind in the abstract, as distinct from the mind of a particular individual and separated from the environment of circumstances, is a fiction only. Yet facts which are partly true gather around this fiction and are naturally described by the help of it. There is also a common type of the mind which is derived from the comparison of many minds with one another and with our own. The phenomena of which Psychology treats are familiar to us, but they are for the most part indefinite; they relate to a something inside the body, which seems also to overleap the limits of space. The operations of this something, when isolated, cannot be analyzed by us or subjected to observation and experiment. And there is another point to be considered. The mind, when thinking, cannot survey that part of itself which is used in thought. It can only be contemplated in the past, that is to say, in the history of the individual or of the world. This is the scientific method of studying the mind. But Psychology has also some other supports, specious rather than real. It is partly sustained by the false analogy of Physical Science and has great expectations from its near relationship to Physiology. We truly remark that there is an infinite complexity of the body corresponding to the infinite subtlety of the mind; we are conscious that they are very nearly connected. But in endeavouring to trace the nature of the connexion we are baffled and disappointed. In our knowledge of them the gulf remains the same: no microscope has ever seen into thought; no reflection on ourselves has supplied the missing link between mind and matter...These are the conditions of this very inexact science, and we shall only know less of it by pretending to know more, or by assigning to it a form or style to which it has not yet attained and is not really entitled.

Experience shows that any system, however baseless and ineffectual, in our own or in any other age, may be accepted and continue to be studied, if it seeks to satisfy some unanswered question or is based upon some ancient tradition, especially if it takes the form and uses the language of inductive philosophy. The fact therefore that such a science exists and is popular, affords no evidence of its truth or value. Many who have pursued it far into detail have never examined the foundations on which it rests. The have been many imaginary subjects of knowledge of which enthusiastic persons have made a lifelong study, without ever asking themselves what is the evidence for them, what is the use of them, how long they will last? They may pass away, like the authors of them, and 'leave not a wrack behind;' or they may survive in fragments. Nor is it only in the Middle Ages, or in the literary desert of China or of India, that such systems have arisen; in our own enlightened age, growing up by the side of Physics, Ethics, and other really progressive sciences, there is a weary waste of knowledge, falsely so-called. There are sham sciences which no logic has ever put to the test, in which the desire for knowledge invents the materials of it.

And therefore it is expedient once more to review the bases of Psychology, lest we should be imposed upon by its pretensions. The study of it may have done good service by awakening us to the sense of inveterate errors familiarized by language, yet it may have fallen into still greater ones; under the pretence of new investigations it may be wasting the lives of those who are engaged in it. It may also be found that the discussion of it will throw light upon some points in the Theaetetus of Plato,—the oldest work on Psychology which has come down to us. The imaginary science may be called, in the language of ancient philosophy, 'a shadow of a part of Dialectic or Metaphysic' (Gorg.).

In this postscript or appendix we propose to treat, first, of the true bases of Psychology; secondly, of the errors into which the students of it are most likely to fall; thirdly, of the principal subjects which are usually comprehended under it; fourthly, of the form which facts relating to the mind most naturally assume.

We may preface the enquiry by two or three remarks:—

(1) We do not claim for the popular Psychology the position of a science at all; it cannot, like the Physical Sciences, proceed by the Inductive Method: it has not the necessity of Mathematics: it does not, like Metaphysic, argue from abstract notions or from internal coherence. It is made up of scattered observations. A few of these, though they may sometimes appear to be truisms, are of the greatest value, and free from all doubt. We are conscious of them in ourselves; we observe them working in others; we are assured of them at all times. For example, we are absolutely certain, (a) of the influence exerted by the mind over the body or by the body over the mind: (b) of the power of association, by which the appearance of some person or the occurrence of some event recalls to mind, not always but often, other persons and events: (c) of the effect of habit, which is strongest when least disturbed by reflection, and is to the mind what the bones are to the body: (d) of the real, though not unlimited, freedom of the human will: (e) of the reference, more or less distinct, of our sensations, feelings, thoughts, actions, to ourselves, which is called consciousness, or, when in excess, self-consciousness: (f) of the distinction of the 'I' and 'Not I,' of ourselves and outward objects. But when we attempt to gather up these elements in a single system, we discover that the links by which we combine them are apt to be mere words. We are in a country which has never been cleared or surveyed; here and there only does a gleam of light come through the darkness of the forest.

(2) These fragments, although they can never become science in the ordinary sense of the word, are a real part of knowledge and may be of great value in education. We may be able to add a good deal to them from our own experience, and we may verify them by it. Self-examination is one of those studies which a man can pursue alone, by attention to himself and the processes of his individual mind. He may learn much about his own character and about the character of others, if he will 'make his mind sit down' and look at itself in the glass. The great, if not the only use of such a study is a practical one,—to know, first, human nature, and, secondly, our own nature, as it truly is.

(3) Hence it is important that we should conceive of the mind in the noblest and simplest manner. While acknowledging that language has been the greatest factor in the formation of human thought, we must endeavour to get rid of the disguises, oppositions, contradictions, which arise out of it. We must disengage ourselves from the ideas which the customary use of words has implanted in us. To avoid error as much as possible when we are speaking of things unseen, the principal terms which we use should be few, and we should not allow ourselves to be enslaved by them. Instead of seeking to frame a technical language, we should vary our forms of speech, lest they should degenerate into formulas. A difficult philosophical problem is better understood when translated into the vernacular.

I.a. Psychology is inseparable from language, and early language contains the first impressions or the oldest experience of man respecting himself. These impressions are not accurate representations of the truth; they are the reflections of a rudimentary age of philosophy. The first and simplest forms of thought are rooted so deep in human nature that they can never be got rid of; but they have been perpetually enlarged and elevated, and the use of many words has been transferred from the body to the mind. The spiritual and intellectual have thus become separated from the material—there is a cleft between them; and the heart and the conscience of man rise above the dominion of the appetites and create a new language in which they too find expression. As the differences of actions begin to be perceived, more and more names are needed. This is the first analysis of the human mind; having a general foundation in popular experience, it is moulded to a certain extent by hierophants and philosophers. (See Introd. to Cratylus.)

b. This primitive psychology is continually receiving additions from the first thinkers, who in return take a colour from the popular language of the time. The mind is regarded from new points of view, and becomes adapted to new conditions of knowledge. It seeks to isolate itself from matter and sense, and to assert its independence in thought. It recognizes that it is independent of the external world. It has five or six natural states or stages:—(1) sensation, in which it is almost latent or quiescent: (2) feeling, or inner sense, when the mind is just awakening: (3) memory, which is decaying sense, and from time to time, as with a spark or flash, has the power of recollecting or reanimating the buried past: (4) thought, in which images pass into abstract notions or are intermingled with them: (5) action, in which the mind moves forward, of itself, or under the impulse of want or desire or pain, to attain or avoid some end or consequence: and (6) there is the composition of these or the admixture or assimilation of them in various degrees. We never see these processes of the mind, nor can we tell the causes of them. But we know them by their results, and learn from other men that so far as we can describe to them or they to us the workings of the mind, their experience is the same or nearly the same with our own.

c. But the knowledge of the mind is not to any great extent derived from the observation of the individual by himself. It is the growing consciousness of the human race, embodied in language, acknowledged by experience, and corrected from time to time by the influence of literature and philosophy. A great, perhaps the most important, part of it is to be found in early Greek thought. In the Theaetetus of Plato it has not yet become fixed: we are still stumbling on the threshold. In Aristotle the process is more nearly completed, and has gained innumerable abstractions, of which many have had to be thrown away because relative only to the controversies of the time. In the interval between Thales and Aristotle were realized the distinctions of mind and body, of universal and particular, of infinite and infinitesimal, of idea and phenomenon; the class conceptions of faculties and virtues, the antagonism of the appetites and the reason; and connected with this, at a higher stage of development, the opposition of moral and intellectual virtue; also the primitive conceptions of unity, being, rest, motion, and the like. These divisions were not really scientific, but rather based on popular experience. They were not held with the precision of modern thinkers, but taken all together they gave a new existence to the mind in thought, and greatly enlarged and more accurately defined man's knowledge of himself and of the world. The majority of them have been accepted by Christian and Western nations. Yet in modern times we have also drifted so far away from Aristotle, that if we were to frame a system on his lines we should be at war with ordinary language and untrue to our own consciousness. And there have been a few both in mediaeval times and since the Reformation who have rebelled against the Aristotelian point of view. Of these eccentric thinkers there have been various types, but they have all a family likeness. According to them, there has been too much analysis and too little synthesis, too much division of the mind into parts and too little conception of it as a whole or in its relation to God and the laws of the universe. They have thought that the elements of plurality and unity have not been duly adjusted. The tendency of such writers has been to allow the personality of man to be absorbed in the universal, or in the divine nature, and to deny the distinction between matter and mind, or to substitute one for the other. They have broken some of the idols of Psychology: they have challenged the received meaning of words: they have regarded the mind under many points of view. But though they may have shaken the old, they have not established the new; their views of philosophy, which seem like the echo of some voice from the East, have been alien to the mind of Europe.

d. The Psychology which is found in common language is in some degree verified by experience, but not in such a manner as to give it the character of an exact science. We cannot say that words always correspond to facts. Common language represents the mind from different and even opposite points of view, which cannot be all of them equally true (compare Cratylus). Yet from diversity of statements and opinions may be obtained a nearer approach to the truth than is to be gained from any one of them. It also tends to correct itself, because it is gradually brought nearer to the common sense of mankind. There are some leading categories or classifications of thought, which, though unverified, must always remain the elements from which the science or study of the mind proceeds. For example, we must assume ideas before we can analyze them, and also a continuing mind to which they belong; the resolution of it into successive moments, which would say, with Protagoras, that the man is not the same person which he was a minute ago, is, as Plato implies in the Theaetetus, an absurdity.

e. The growth of the mind, which may be traced in the histories of religions and philosophies and in the thoughts of nations, is one of the deepest and noblest modes of studying it. Here we are dealing with the reality, with the greater and, as it may be termed, the most sacred part of history. We study the mind of man as it begins to be inspired by a human or divine reason, as it is modified by circumstances, as it is distributed in nations, as it is renovated by great movements, which go beyond the limits of nations and affect human society on a scale still greater, as it is created or renewed by great minds, who, looking down from above, have a wider and more comprehensive vision. This is an ambitious study, of which most of us rather 'entertain conjecture' than arrive at any detailed or accurate knowledge. Later arises the reflection how these great ideas or movements of the world have been appropriated by the multitude and found a way to the minds of individuals. The real Psychology is that which shows how the increasing knowledge of nature and the increasing experience of life have always been slowly transforming the mind, how religions too have been modified in the course of ages 'that God may be all and in all.' E pollaplasion, eoe, to ergon e os nun zeteitai prostatteis.

f. Lastly, though we speak of the study of mind in a special sense, it may also be said that there is no science which does not contribute to our knowledge of it. The methods of science and their analogies are new faculties, discovered by the few and imparted to the many. They are to the mind, what the senses are to the body; or better, they may be compared to instruments such as the telescope or microscope by which the discriminating power of the senses, or to other mechanical inventions, by which the strength and skill of the human body is so immeasurably increased.

II. The new Psychology, whatever may be its claim to the authority of a science, has called attention to many facts and corrected many errors, which without it would have been unexamined. Yet it is also itself very liable to illusion. The evidence on which it rests is vague and indefinite. The field of consciousness is never seen by us as a whole, but only at particular points, which are always changing. The veil of language intercepts facts. Hence it is desirable that in making an approach to the study we should consider at the outset what are the kinds of error which most easily affect it, and note the differences which separate it from other branches of knowledge.

a. First, we observe the mind by the mind. It would seem therefore that we are always in danger of leaving out the half of that which is the subject of our enquiry. We come at once upon the difficulty of what is the meaning of the word. Does it differ as subject and object in the same manner? Can we suppose one set of feelings or one part of the mind to interpret another? Is the introspecting thought the same with the thought which is introspected? Has the mind the power of surveying its whole domain at one and the same time?—No more than the eye can take in the whole human body at a glance. Yet there may be a glimpse round the corner, or a thought transferred in a moment from one point of view to another, which enables us to see nearly the whole, if not at once, at any rate in succession. Such glimpses will hardly enable us to contemplate from within the mind in its true proportions. Hence the firmer ground of Psychology is not the consciousness of inward feelings but the observation of external actions, being the actions not only of ourselves, but of the innumerable persons whom we come across in life.

b. The error of supposing partial or occasional explanation of mental phenomena to be the only or complete ones. For example, we are disinclined to admit of the spontaneity or discontinuity of the mind—it seems to us like an effect without a cause, and therefore we suppose the train of our thoughts to be always called up by association. Yet it is probable, or indeed certain, that of many mental phenomena there are no mental antecedents, but only bodily ones.

c. The false influence of language. We are apt to suppose that when there are two or more words describing faculties or processes of the mind, there are real differences corresponding to them. But this is not the case. Nor can we determine how far they do or do not exist, or by what degree or kind of difference they are distinguished. The same remark may be made about figures of speech. They fill up the vacancy of knowledge; they are to the mind what too much colour is to the eye; but the truth is rather concealed than revealed by them.

d. The uncertain meaning of terms, such as Consciousness, Conscience, Will, Law, Knowledge, Internal and External Sense; these, in the language of Plato, 'we shamelessly use, without ever having taken the pains to analyze them.'

e. A science such as Psychology is not merely an hypothesis, but an hypothesis which, unlike the hypotheses of Physics, can never be verified. It rests only on the general impressions of mankind, and there is little or no hope of adding in any considerable degree to our stock of mental facts.

f. The parallelism of the Physical Sciences, which leads us to analyze the mind on the analogy of the body, and so to reduce mental operations to the level of bodily ones, or to confound one with the other.

g. That the progress of Physiology may throw a new light on Psychology is a dream in which scientific men are always tempted to indulge. But however certain we may be of the connexion between mind and body, the explanation of the one by the other is a hidden place of nature which has hitherto been investigated with little or no success.

h. The impossibility of distinguishing between mind and body. Neither in thought nor in experience can we separate them. They seem to act together; yet we feel that we are sometimes under the dominion of the one, sometimes of the other, and sometimes, both in the common use of language and in fact, they transform themselves, the one into the good principle, the other into the evil principle; and then again the 'I' comes in and mediates between them. It is also difficult to distinguish outward facts from the ideas of them in the mind, or to separate the external stimulus to a sensation from the activity of the organ, or this from the invisible agencies by which it reaches the mind, or any process of sense from its mental antecedent, or any mental energy from its nervous expression.

i. The fact that mental divisions tend to run into one another, and that in speaking of the mind we cannot always distinguish differences of kind from differences of degree; nor have we any measure of the strength and intensity of our ideas or feelings.

j. Although heredity has been always known to the ancients as well as ourselves to exercise a considerable influence on human character, yet we are unable to calculate what proportion this birth-influence bears to nurture and education. But this is the real question. We cannot pursue the mind into embryology: we can only trace how, after birth, it begins to grow. But how much is due to the soil, how much to the original latent seed, it is impossible to distinguish. And because we are certain that heredity exercises a considerable, but undefined influence, we must not increase the wonder by exaggerating it.

k. The love of system is always tending to prevail over the historical investigation of the mind, which is our chief means of knowing it. It equally tends to hinder the other great source of our knowledge of the mind, the observation of its workings and processes which we can make for ourselves.

l. The mind, when studied through the individual, is apt to be isolated—this is due to the very form of the enquiry; whereas, in truth, it is indistinguishable from circumstances, the very language which it uses being the result of the instincts of long-forgotten generations, and every word which a man utters being the answer to some other word spoken or suggested by somebody else.

III. The tendency of the preceding remarks has been to show that Psychology is necessarily a fragment, and is not and cannot be a connected system. We cannot define or limit the mind, but we can describe it. We can collect information about it; we can enumerate the principal subjects which are included in the study of it. Thus we are able to rehabilitate Psychology to some extent, not as a branch of science, but as a collection of facts bearing on human life, as a part of the history of philosophy, as an aspect of Metaphysic. It is a fragment of a science only, which in all probability can never make any great progress or attain to much clearness or exactness. It is however a kind of knowledge which has a great interest for us and is always present to us, and of which we carry about the materials in our own bosoms. We can observe our minds and we can experiment upon them, and the knowledge thus acquired is not easily forgotten, and is a help to us in study as well as in conduct.

The principal subjects of Psychology may be summed up as follows:—

a. The relation of man to the world around him,—in what sense and within what limits can he withdraw from its laws or assert himself against them (Freedom and Necessity), and what is that which we suppose to be thus independent and which we call ourselves? How does the inward differ from the outward and what is the relation between them, and where do we draw the line by which we separate mind from matter, the soul from the body? Is the mind active or passive, or partly both? Are its movements identical with those of the body, or only preconcerted and coincident with them, or is one simply an aspect of the other?

b. What are we to think of time and space? Time seems to have a nearer connexion with the mind, space with the body; yet time, as well as space, is necessary to our idea of either. We see also that they have an analogy with one another, and that in Mathematics they often interpenetrate. Space or place has been said by Kant to be the form of the outward, time of the inward sense. He regards them as parts or forms of the mind. But this is an unfortunate and inexpressive way of describing their relation to us. For of all the phenomena present to the human mind they seem to have most the character of objective existence. There is no use in asking what is beyond or behind them; we cannot get rid of them. And to throw the laws of external nature which to us are the type of the immutable into the subjective side of the antithesis seems to be equally inappropriate.

c. When in imagination we enter into the closet of the mind and withdraw ourselves from the external world, we seem to find there more or less distinct processes which may be described by the words, 'I perceive,' 'I feel,' 'I think,' 'I want,' 'I wish,' 'I like,' 'I dislike,' 'I fear,' 'I know,' 'I remember,' 'I imagine,' 'I dream,' 'I act,' 'I endeavour,' 'I hope.' These processes would seem to have the same notions attached to them in the minds of all educated persons. They are distinguished from one another in thought, but they intermingle. It is possible to reflect upon them or to become conscious of them in a greater or less degree, or with a greater or less continuity or attention, and thus arise the intermittent phenomena of consciousness or self-consciousness. The use of all of them is possible to us at all times; and therefore in any operation of the mind the whole are latent. But we are able to characterise them sufficiently by that part of the complex action which is the most prominent. We have no difficulty in distinguishing an act of sight or an act of will from an act of thought, although thought is present in both of them. Hence the conception of different faculties or different virtues is precarious, because each of them is passing into the other, and they are all one in the mind itself; they appear and reappear, and may all be regarded as the ever-varying phases or aspects or differences of the same mind or person.

d. Nearest the sense in the scale of the intellectual faculties is memory, which is a mode rather than a faculty of the mind, and accompanies all mental operations. There are two principal kinds of it, recollection and recognition,—recollection in which forgotten things are recalled or return to the mind, recognition in which the mind finds itself again among things once familiar. The simplest way in which we can represent the former to ourselves is by shutting our eyes and trying to recall in what we term the mind's eye the picture of the surrounding scene, or by laying down the book which we are reading and recapitulating what we can remember of it. But many times more powerful than recollection is recognition, perhaps because it is more assisted by association. We have known and forgotten, and after a long interval the thing which we have seen once is seen again by us, but with a different feeling, and comes back to us, not as new knowledge, but as a thing to which we ourselves impart a notion already present to us; in Plato's words, we set the stamp upon the wax. Every one is aware of the difference between the first and second sight of a place, between a scene clothed with associations or bare and divested of them. We say to ourselves on revisiting a spot after a long interval: How many things have happened since I last saw this! There is probably no impression ever received by us of which we can venture to say that the vestiges are altogether lost, or that we might not, under some circumstances, recover it. A long-forgotten knowledge may be easily renewed and therefore is very different from ignorance. Of the language learnt in childhood not a word may be remembered, and yet, when a new beginning is made, the old habit soon returns, the neglected organs come back into use, and the river of speech finds out the dried-up channel.

e. 'Consciousness' is the most treacherous word which is employed in the study of the mind, for it is used in many senses, and has rarely, if ever, been minutely analyzed. Like memory, it accompanies all mental operations, but not always continuously, and it exists in various degrees. It may be imperceptible or hardly perceptible: it may be the living sense that our thoughts, actions, sufferings, are our own. It is a kind of attention which we pay to ourselves, and is intermittent rather than continuous. Its sphere has been exaggerated. It is sometimes said to assure us of our freedom; but this is an illusion: as there may be a real freedom without consciousness of it, so there may be a consciousness of freedom without the reality. It may be regarded as a higher degree of knowledge when we not only know but know that we know. Consciousness is opposed to habit, inattention, sleep, death. It may be illustrated by its derivative conscience, which speaks to men, not only of right and wrong in the abstract, but of right and wrong actions in reference to themselves and their circumstances.

f. Association is another of the ever-present phenomena of the human mind. We speak of the laws of association, but this is an expression which is confusing, for the phenomenon itself is of the most capricious and uncertain sort. It may be briefly described as follows. The simplest case of association is that of sense. When we see or hear separately one of two things, which we have previously seen or heard together, the occurrence of the one has a tendency to suggest the other. So the sight or name of a house may recall to our minds the memory of those who once lived there. Like may recall like and everything its opposite. The parts of a whole, the terms of a series, objects lying near, words having a customary order stick together in the mind. A word may bring back a passage of poetry or a whole system of philosophy; from one end of the world or from one pole of knowledge we may travel to the other in an indivisible instant. The long train of association by which we pass from one point to the other, involving every sort of complex relation, so sudden, so accidental, is one of the greatest wonders of mind...This process however is not always continuous, but often intermittent: we can think of things in isolation as well as in association; we do not mean that they must all hang from one another. We can begin again after an interval of rest or vacancy, as a new train of thought suddenly arises, as, for example, when we wake of a morning or after violent exercise. Time, place, the same colour or sound or smell or taste, will often call up some thought or recollection either accidentally or naturally associated with them. But it is equally noticeable that the new thought may occur to us, we cannot tell how or why, by the spontaneous action of the mind itself or by the latent influence of the body. Both science and poetry are made up of associations or recollections, but we must observe also that the mind is not wholly dependent on them, having also the power of origination.

There are other processes of the mind which it is good for us to study when we are at home and by ourselves,—the manner in which thought passes into act, the conflict of passion and reason in many stages, the transition from sensuality to love or sentiment and from earthly love to heavenly, the slow and silent influence of habit, which little by little changes the nature of men, the sudden change of the old nature of man into a new one, wrought by shame or by some other overwhelming impulse. These are the greater phenomena of mind, and he who has thought of them for himself will live and move in a better-ordered world, and will himself be a better-ordered man.

At the other end of the 'globus intellectualis,' nearest, not to earth and sense, but to heaven and God, is the personality of man, by which he holds communion with the unseen world. Somehow, he knows not how, somewhere, he knows not where, under this higher aspect of his being he grasps the ideas of God, freedom and immortality; he sees the forms of truth, holiness and love, and is satisfied with them. No account of the mind can be complete which does not admit the reality or the possibility of another life. Whether regarded as an ideal or as a fact, the highest part of man's nature and that in which it seems most nearly to approach the divine, is a phenomenon which exists, and must therefore be included within the domain of Psychology.

IV. We admit that there is no perfect or ideal Psychology. It is not a whole in the same sense in which Chemistry, Physiology, or Mathematics are wholes: that is to say, it is not a connected unity of knowledge. Compared with the wealth of other sciences, it rests upon a small number of facts; and when we go beyond these, we fall into conjectures and verbal discussions. The facts themselves are disjointed; the causes of them run up into other sciences, and we have no means of tracing them from one to the other. Yet it may be true of this, as of other beginnings of knowledge, that the attempt to put them together has tested the truth of them, and given a stimulus to the enquiry into them.

Psychology should be natural, not technical. It should take the form which is the most intelligible to the common understanding, because it has to do with common things, which are familiar to us all. It should aim at no more than every reflecting man knows or can easily verify for himself. When simple and unpretentious, it is least obscured by words, least liable to fall under the influence of Physiology or Metaphysic. It should argue, not from exceptional, but from ordinary phenomena. It should be careful to distinguish the higher and the lower elements of human nature, and not allow one to be veiled in the disguise of the other, lest through the slippery nature of language we should pass imperceptibly from good to evil, from nature in the higher to nature in the neutral or lower sense. It should assert consistently the unity of the human faculties, the unity of knowledge, the unity of God and law. The difference between the will and the affections and between the reason and the passions should also be recognized by it.

Its sphere is supposed to be narrowed to the individual soul; but it cannot be thus separated in fact. It goes back to the beginnings of things, to the first growth of language and philosophy, and to the whole science of man. There can be no truth or completeness in any study of the mind which is confined to the individual. The nature of language, though not the whole, is perhaps at present the most important element in our knowledge of it. It is not impossible that some numerical laws may be found to have a place in the relations of mind and matter, as in the rest of nature. The old Pythagorean fancy that the soul 'is or has in it harmony' may in some degree be realized. But the indications of such numerical harmonies are faint; either the secret of them lies deeper than we can discover, or nature may have rebelled against the use of them in the composition of men and animals. It is with qualitative rather than with quantitative differences that we are concerned in Psychology. The facts relating to the mind which we obtain from Physiology are negative rather than positive. They show us, not the processes of mental action, but the conditions of which when deprived the mind ceases to act. It would seem as if the time had not yet arrived when we can hope to add anything of much importance to our knowledge of the mind from the investigations of the microscope. The elements of Psychology can still only be learnt from reflections on ourselves, which interpret and are also interpreted by our experience of others. The history of language, of philosophy, and religion, the great thoughts or inventions or discoveries which move mankind, furnish the larger moulds or outlines in which the human mind has been cast. From these the individual derives so much as he is able to comprehend or has the opportunity of learning.

     'Alone being remains unmoved which is the name for all,'

     O gar arche men o me oide, teleute de kai ta metaxu ex ou me
     oide sumpeplektai, tis mechane ten toiauten omologian pote
     epistemen genesthai; Plato Republic.

     Monon gar auto legeiv, osper gumnon kai aperemomenon apo ton
     onton apanton, adunaton.  Soph.