The truth may be out there, but lies are inside your head.

You need to believe in things that aren't true. How else can they become?

That's why it's always worth having a few philosophers around the place. One minute it's all is truth beauty and is beauty truth, and does a falling tree in the forest make a sound if there's no one there to hear it, and then just when you think they're going to start dribbling one of 'em says, incidentally, putting a thirty-foot parabolic reflector on a high place to shoot the rays of the sun at an enemy's ships would be a very interesting demonstration of optical principles.

This man was so absent-mindedly clever that he could paint pictures that didn’t just follow you around the room but went home with you and did the washing-up.

Vimes had got around to a Clean Desk policy. It was a Clean Floor strategy that eluded him at the moment.

Just because someone's a member of an ethnic minority doesn't mean they're not a nasty small-minded little jerk [...]

I had a deprived childhood, you see. I had lots of other kids to play with and my parents bought me outdoor toys and refused to ill-treat me, so it never occurred to me to seek solitary consolation with a good book.