“Plato’s Allegory of the Cave”Socrates asks Glaucon to imagine a cave with prisoners, who have been in the cave for their entire lives, with their legs and necks shackled by chains, so that the movement of their face is limited, and they can’t see nothing, but the wall and shadows in front of them. This restricted movement limits their vision only to the wall, limiting the scope of anything beyond it.
There is also a fire blazing at a distance, above and behind the prisoners, and between the fire and the prisoners. The shadows of all sorts of objects, appear on the wall. Providing a view for the prisoners, and say there was an echo/voices that came from the wall because of the other people. The prisoners would perceive it to be the voices of those passing shadows.
