“Picture men dwelling in a sort of subterranean cavern,” famously says Plato's Socrates in book seven of The Republic, unable “to see anything besides the shadows that are projected on the wall opposite them by the glow of the fire.” These people, as Socrates tells Glaucon, “are very much like us humans,” taking insubstantial appearances for the realities of which they are merely “shadows.” For Plato, these shadows are the immaterial and deceptive forms of what is real, which can only be known when one escapes from the cave and sees the sun and the world it illuminates. In Plato's allegory, the sunlit world reveals the ideal forms of things that can be apprehended only by the intellect, while the cave's shadows represent the world of material objects accessible through the senses.
Of course, as visual phenomena, shadows are exactly what Plato's allegorical shadows are not, although they pose...
