ABSTRACT
Imagine a cave. Prisoners are chained facing its far wall. They’ve been kept there all their lives and their heads are held fixed so that they can’t see anything except the wall of the cave. Behind them there is a fire and between the fire and their backs a road. Along the road various people walk casting their shadows on the cave wall; some of them carry models of animals which also cast shadows. The prisoners inside the cave only ever see shadows. They believe the shadows are the real things because they don’t know any better. But in fact they never see real people.
