Definition of Allusion: 

An allusion is a reference to another literary work, historical text or event, myth, song, or other cultural artifact. The purpose of the reference is not explained, which means allusions must draw on knowledge shared between the writer and the reader. It is the task of the reader to uncover the hidden meaning in allusion. Allusions give writers the ability to add depth to their works by drawing on, or building upon, ideas or emotions associated with other texts or events.

Examples of Allusion in Literature:

“No! I am not Prince Hamlet, nor was meant to be; 
Am an attendant lord, one that will do 
To swell a progress, start a scene or two, 
Advise the prince; no doubt, an easy tool, 
Deferential, glad to be of use, 
Politic, cautious, and meticulous; 
Full of high sentence, but a bit obtuse; 
At times, indeed, almost ridiculous— 
Almost, at times, the Fool.”
—T.S. Eliot’s “The Love Song of J. Alfred Prufrock” 

This example features an allusion to Hamlet, Shakespeare’s famous play. The narrator does not feel as though he can fill the shoes of a protagonist as Hamlet does, instead relegating himself to the role of a side character. He likens himself to “The Fool,” an archetypical humorous role in Shakespeare’s plays. The description Eliot uses could fit either Polonius or Yorick, who both embody aspects of the fool’s role and affect Hamlet, revealing Prufrock’s desire to be useful without claiming the spotlight for himself.

“A belt of straw and ivy buds,
With coral clasps and amber studs:
And if these pleasures may thee move,
Come live with me, and be my love.”
—Christopher Marlowe’s “The Passionate Shepherd to His Love”

“Thy belt of straw and Ivy buds,
The Coral clasps and amber studs,
All these in me no means can move
To come to thee and be thy love.”
—Sir Walter Raleigh’s “The Nymph’s Reply to the Shepherd”

This set of examples represents a much more directly referential type of allusion: the response. Raleigh wrote his poem as a direct response to Marlowe’s, as is evidenced by his identical meter and imitative diction. Rather than simply making a passing reference, as most allusions do, Raleigh is relying on the reader’s knowledge of Marlowe’s poem in order for his poem to be understood. If the reader understands the allusion, Raleigh’s text takes on a more significant meaning and can be read as a criticism of the pastoral tradition which Marlowe was glorifying.