Book 7 of Plato's Republic opens with the allegory of the cave. Socrates describes a group of prisoners who have been chained up in a cave since childhood. They are facing a wall and cannot see anything outside the cave, only the shadows cast on the wall in front of them. All the prisoners mistake these shadows for reality until one of them escapes and goes out into the light of day, where he sees real objects at last. Socrates says that the visible world is like the cave, while the world of Forms understood by the philosopher is the true reality. Education is the process of teaching people this, though few are willing to learn.

Socrates returns to the topic of the education of the guardians who would rule over his ideal city. After a course of study involving poetry, music, and military training, the best students should go on to receive a rigorous education in mathematics and logic, with a view to making them philosophers. They must be taught the art of debating—not to win arguments but to arrive at the truth—before they begin a political career.