It is an allegory formulated by the philosopher Plato, in which prisoners, bound with chains in a cave, spend their lives observing reflected figures projected by a light behind them, without knowing that that light is the Sun and the figures are shadows of free people. The moral of this story is that those who do not know the idea of Good (represented by the Sun) are slaves who see nothing but shadows projected on a screen that we cannot help but regard as reality. At the end of the story, one of the slaves is freed and finds the truth, gazes at the sun and realizes that he was not free (to have knowledge of the truth). He then decides to return to the cave and tell the truth to the rest of the slaves, but they do not believe him and kill him, meaning that either most of us do not accept the truth or that it must be experienced individually in order to be apprehended.
