Plato's "Allegory of the Cave" (one chapter of The Republic) is a philosophical allegory based on the concept of enlightenment.  Here are links to various translations of Plato's text and a website which ponders similarities between Plato's well-known idea and the recent movies The Matrix and The Truman Show. 

The version of Plato's "Allegory of the Cave" with which I am most familiar. 

A similar version of Plato's "Allegory of the Cave" by Benjamin Jowett.

An explanation of Plato's "Allegory".  Especially interesting for the visual representation of the cave.

A comparison of Plato's Allegory to The Matrix and The Truman Show.

A comparison of Plato's "Allegory" and The Matrix.  (Cool idea, but Dew's typos are bothersome.)