The Allegory of the Cave (514a–520d)

Prisoners chained since childhood facing a wall; behind them a low parapet like a puppeteer's screen, and behind that a fire. Carriers pass along the parapet holding up figures of men and animals in wood and stone. The prisoners see only the shadows, hear only the echoes, and name those the world. One is loosed, turned around, dragged up a rough and steep road, and eventually looks at the sun. Then he goes back down.

Six pages that organise this entire annex. The wing draws it as a walk rather than a diagram, because Plato tells it as a journey with a turn in the middle, and giving it a figure would be a reskin of somebody else's geometry.