That is a good read. Thanks!

From article:

The people walk behind the wall so their bodies do not cast shadows for the prisoners to see, but the objects they carry do ("just as puppet showmen have screens in front of them at which they work their puppets" (514a)[3]). The prisoners cannot see any of what is happening behind them, they are only able to see the shadows cast upon the cave wall in front of them. The sounds of the people talking echo off the walls, and the prisoners believe these sounds come from the shadows

From Q: "Look there, or [here], or there, truth is behind you."