Plato used the analogy of the cave to illustrate his idea of forms. The analogy goes like this:
Imagine several prisoners who have been chained up in a cave for all of their lives. They have never been outside the cave. They face a wall in the cave and they can never look at the entrance of the cave. Sometimes animals, birds, people, or other objects pass by the entrance of the cave casting a shadow on the wall inside the cave. The prisoners see the shadows on the wall and mistakenly view the shadows as reality.
However, one man breaks free from his chains and runs out of the cave. For the first time, he sees the real world and now knows that it is far beyond the shadows he had been seeing. He sees real birds and animals, not just shadows of birds and animals.
This man is excited about what he sees and he goes back to his fellow prisoners in the cave to tell them about the real world. But to his astonishment, they don’t believe him. In fact, they are angry with him. They say the shadows are reality and that the escaped prisoner is crazy for saying otherwise.
POINT OF THE CAVE ANALOGY: According to Plato, the world outside the cave represents the world of forms while the shadows on the wall represent objects in the physical world. The escape of the prisoner represents philosophical enlightenment and the realization that forms are the true reality. Most people are like the prisoners in the cave. They think the shadows are reality. Philosophers, though, are like the man who escapes the cave and sees the real world. They have true knowledge.