Plato
Book VII of The Republic
The Allegory of the Cave
Here's a little story from Plato's most famous book, The Republic. Socrates is talking to a young follower of his named Glaucon, and is telling him this fable to illustrate what it's like to be a philosopher -- a lover of wisdom: Most people, including ourselves, live in a world of relative ignorance. We are even comfortable with that ignorance, because it is all we know. When we first start facing truth, the process may be frightening, and many people run back to their old lives. But if you continue to seek truth, you will eventually be able to handle it better. In fact, you want more! It's true that many people around you now may think you are weird or even a danger to society, but you don't care. Once you've tasted the truth, you won't ever want to go back to being ignorant!
[Socrates is speaking with Glaucon]
[Socrates:] And now, I said, let me show in a figure how far our nature is enlightened or unenlightened: --Behold! human beings living in a underground den, which has a mouth open towards the light and reaching all along the den; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning round their heads. Above and behind them a fire is blazing at a distance, and between the fire and the prisoners there is a raised way; and you will see, if you look, a low wall built along the way, like the screen which marionette players have in front of them, over which they show the puppets.
[Glaucon:] I see.
And do you see, I said, men passing along the wall carrying all sorts of vessels, and statues and figures of animals made of wood and stone and various m ...