Answer:
Plato begins by having Socrates ask Glaucon to imagine a cave where people have been imprisoned from childhood (important to note that they were (based on text) imprisoned from childhood not from birth). These prisoners are chained so that their legs and necks are fixed, forcing them to gaze at the wall in front of them and not look around at the cave, each other, or themselves. Behind the prisoners is a fire, and between the fire and the prisoners is a raised walkway with a low wall, behind which people walk carrying objects or puppets "of men and other living things".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".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.
Socrates suggests that the shadows are reality for the prisoners because they have never seen anything else; they do not realize that what they see are shadows of objects in front of a fire, much less that these objects are inspired by real things outside the cave which they do not see]
The fire, or human made light, and the puppets, used to make shadows, are done by the artists. This can be compared to how illusions are made with light and sound today, with electronics, videos, movies, and 3D visuals. Plato, however, indicates that the fire is also the political doctrine that is taught in a nation state. The artists use light and shadows to teach the dominant doctrines of a time and place.
Also, few humans will ever escape the cave. This is not some easy task, and only a true philosopher, with decades of preparation, would be able to leave the cave, up the steep incline. Most humans will live at the bottom of the cave, and a small few will be the major artists that project the shadows with the use of human made light.
