I was recently reminded of a scene from The Silver Chair, after having a rather depressing conversation with several colleagues who were happily convinced that their soulless lives of drink and loose women were as good as it gets.
Do you remember the scene in the underworld where the witch is trying to cast a spell upon our heroes, trying to convince them that they have simply imagined the real world above? She tries to tell them that they have looked at a lamp and imagined a larger one, and called it "the sun"; they have seen her cat and imagined a greater one, and called him "Aslan." She has just about got them convinced when Puddleglum stamps out her magical fire with his webby foot and proceeds to give one of the greatest speeches in all literature:
Suppose we have only dreamed, or made up, all those things – trees and grass and sun and moon and stars and Aslan himself. Suppose we have. Then all I can say is that, in that case, the made-up things seem a good deal more important than the real ones. Suppose this black pit of a kingdom of yours is the only real world. Well, it strikes me as a pretty poor one. And that’s a funny thing, when you come to think of it. We’re just babies making up a game, if you’re right. But four babies playing a game can make a play-world which licks your real world hollow. That’s why I’m going to stand by the play-world. I'm on Aslan's side even if there isn't any Aslan to lead it. I'm going to live as like a Narnian as I can even if there isn't any Narnia. So, thanking you kindly for our supper, if these two gentlemen and the young lady are ready, we’re leaving your court at once and setting out in the dark to spend our lives looking for the Overland. Not that our lives will be very long, I should think; but that’s a small loss if the world’s as dull a place as you say.
~Puddleglum, The Silver Chair, Chapter XII: The Queen of the Underworld