Catch-22
By Joseph Heller

A satire on war, I suppose, but that's a pretty broad and uninteresting category by itself. Catch-22 plays with the first principles of existence: Out of a million possible examples, how about this? One soldier named Dunbar notices that time passes more slowly when you're bored; he therefore sets about cultivating a state of perfect boredom in which time will actually stop, allowing him to live forever. Except that thought itself is interesting, and so hastens his death. And so on. Breathtakingly brilliant stuff.