Plato wrote The Allegory of the Cave using the Socratic
Method, a dialog between a teacher and student. It is taken
from a larger work entitled the Republic. Here is a very, very brief summary:
Suppose that there is a group of people who have lived their entire
lives trapped in a cave lit by a large fire behind them. Chained in place, these
people can see nothing but shadows projected on a wall in front of them.
They cannot truly comprehend what they see, since they are prevented from
grasping its true source and nature.
Now suppose that one of these human beings manages to break the chains, climb
through the passage, and escape the cave. With
eyes accustomed only to the dim light of the cave, this individual will at
first be blinded by the brightness of the world. But after some
time and effort, he will become able to appreciate the beauty of
the world.
Finally, suppose that this escapee returns to the cave,
trying to persuade the others that there is another, better, real world than the
one in the cave. They are unlikely to be impressed by his pleas, especially
since, having travelled to the bright surface world, he is now clumsy in the dim
cave.