Plato's "Myth of the cave" is an argument that we can't be sure we know reality. This story illustrates Plato's idealism. The objects we see, hear, touch are shadows of the real things. The reason is human beings don't have a full sense of a real and complete life because of the world.
In this story, Plato use a dialog between a teacher and student, it describes a group of prisoners chained inside a cave, sit behind a fire, they can't see each other or the nature of reality, or the heavens, only able to look forward. The fire casts shadows on the cave wall, which they see and it is the only reality they know. They can't truly comprehend what they see, as they are prevented from its true source and nature. One day one of the prisoners having managed to free himself from his chains escape from the cave and see the truth.
He will at first be blinded by the brightness of the world. But after some time and effort, he will be able to see anything that resembled what he knew as reality before. He will be able to see the entire world around him, and appreciate the beauty of the world. Through this knowledge he will become aware of his place in the world. Finally he goes back again into the darkened cave to tell the people still chained up in the cave about the real word outside. Accustomed to the outside world full of nature light, the rescuer in the darkness of the cave and looks foolish to those inside. The cave dwellers laughing at him for his crazy ideas and insist that they are perfectly happy where they are. They would not believe and would ridicule him, and if they could lay hands on him, they would kill him. However, the prisoner would know what is right, even if all those around him disbelieve it.
In Plato's "Myth of the cave" points a person who is set free, and goes out to see the real world, and what lies behind the shadows of light that we see. Having been enlightened to the nature of reality, it is not easy to explain this to others. Humans in their unenlightened beginnings are symbolized as imprisoned at the back of a dark cave. The shadowy environment of the cave symbolizes for Plato the physical world of appearances. Escape into the outside the cave symbolizes the transition to the real world, the world of full and perfect being, the world of forms, which is the proper object of knowledge.