The “Allegory of the Cave” starts off as a story told by Socrates to Glaucon. In this story, a group of people live in a cave underground. They are bound and unable to move or turn their heads, and so can only look straight in front of them.
Before them is a wall and behind them a fire burns. Others in the cave pass before the fire holding objects which cast shadows on the wall.
Later, a prisoner is released and taken to the outside world. At first he recoils from the bright light, but he gradually adjusts until he sees the outside world just as if he had lived his whole life above ground instead of in a cave. After being set free, I wouldn’t return to the cave. Plato's Allegory of the Cave is a symbol for the contrasts between ideas and what we perceive as reality.
The prisoners in the cave are as ignorant of the truth as Glaucon was, if he relied solely on what he saw. The prisoners, having lived their whole life in the cave, would look upon the shadows they saw and recognize them as reality. In the same way, Glaucon and others like him believed what they saw and experienced was in fact the reality of the Universe. Conversely, Plato believed that the truth of the Universe was hidden and that the way to discover it was not through observation of the surrounding world but through logic and reasoning. Most people prefer to remain in chains and to see only shadows of the truth. Only the few -- and the wise -- are willing to free themselves from the shackles and look the truth in the face, even if it is blinding at first.
The Theory of Forms typically refers to the belief expressed by Socrates in some of Plato's dialogues, that the material world as it seems to us is not the real world, but only an image or copy of the real world. Just like the people in the cave, what we perceive...