"I hold the world but as the world, Gratiano;(80)
A stage, where every man must play a part,
And mine a sad one...."See in text(Act I - Scene I)
In claiming that the world is a stage, Antonio highlights the affected nature of his sadness. He is playing the role of melancholy rather than actually feeling melancholic. Gratiano picks up on this hole in Antonio's metaphor and exploits it to insinuate that Antonio is only sad so that he can appear more profound to others. This exchange introduces the theme of playing and perception early on in the play.
"Shall I bend low, and in a bondman's key,
With 'bated breath, and whispering humbleness,..."See in text(Act I - Scene III)
Here "bated breath" means holding one's tongue or meekly waiting for something to happen. Shylock uses this term to point out the Christian's hypocrisy in expecting him to loan them 3,000 ducats while believing that he should be subservient to them.
"I will buy(30)
with you, sell with you, talk with you, walk with you, and
so following; but I will not eat with you..."See in text(Act I - Scene III)
Unlike Antonio's friends who seem to have few beliefs, except for the belief in the power and importance of money, Shylock believes in his religion over money. He will not sacrifice his religion in order to make this business deal. In this sense, a sharp distinction is made between the Christians and Shylock: Shylock is the more principled of the two.
"All that glisters is not gold,..."See in text(Act II - Scene VII)
There is literary evidence for this proverb that pre-date Shakespeare's play. However, The Merchant of Venice made this saying universally recognized. "All that glitters is not gold" accurately sums up the theme of the play: external appearances often belie the internal state of something.
"What's here? the portrait of a blinking idiot,
Presenting me a schedule!..."See in text(Act II - Scene IX)
Arragon opens the casket to find a mirror that reflects his own face. His lines can be played to show his disappointment and self-reflection, or as angry since he truly believed that he would choose the right casket.
" I am a Jew: hath not a Jew eyes? hath not a Jew
hands, organs, dimensions, senses, affections, passions?
fed with the same food, hurt with the same weapons,
subject to the same diseases, healed by the same means,
warmed and cooled by the same winter and summer, as(55)
a Christian is? If you prick us, do we not bleed? ..."See in text(Act III - Scene I)
This is the most famous speech in this play and one of the most famous speeches in the Shakespeare cannon. Notice that for all of the antisemitism racked against Shylock, Shylock is given the best and most memorable lines in the play. The presence of this speech offers an alternative reading of the play in which it is a tragedy: Shylock is the sympathetic character who wrongfully loses at the end of the play.
"cover is the word...."See in text(Act III - Scene V)
Shakespeare uses "— is the word" multiple times throughout his plays. Launcelot's use of it here is the earliest example. It's frequency suggests that Shakespeare based this saying off a proverb that was popular at his time. However, it could also be something that he invented which he grew fond of an used often.
"The quality of mercy is not strain'd,
It droppeth, as the gentle rain from heaven..."See in text(Act IV - Scene I)
Notice the religious underpinnings of this speech. Portia makes an argument about mercy that is set within a Christian context; she argues that Shylock should be merciful because it will bring him closer to God. However, in holding Shylock to a Christian standard of mercy, Portia disregards both the law and Shylock's Judaism.
"The pound of flesh, which I demand of him,(100)
Is dearly bought; 'tis mine, and I will have it:..."See in text(Act IV - Scene I)
"Dearly bought" can either mean expensively, or paid for in grave personal loss. This line can be performed and heard in two ways. It is either a sign of the money-hungry Shylock claiming that his loss of money means he deserves his pound of flesh, or it is a sign of his humanity. Shylock has lost everything, including his daughter, and now all that is left is his "dearly bought" revenge.
"The man that hath no music in himself,
Nor is not mov'd with concord of sweet sounds,
Is fit for treasons,..."See in text(Act V)
Here, Lorenzo claims that there is something inherently wrong with people who do not like music. They are deceptive and lower than animals as animals are even moved by "sweet sounds." Shylock and Jessica are the only two characters in the play who express distaste for music, suggesting that they have a darker disposition or propensity for treason. Notice that these lines occur after Shylock has been defeated and Portia has claimed that Christians should have mercy. This suggests that the Christians have learned nothing and that the antisemitic hierarchy persists in Venice.