Terry Pratchett: Doing (page 3)

“If you really want to upset a witch, do her a favor which she has no means of repaying. The unfulfilled obligation will nag at her like a hangnail.”

“The trouble with life was that you didn’t get a chance to practice before doing it for real.”

“Don't you understand?" snarled Rincewind. "We are going over the Edge, godsdammit!"
"Can't we do anything about it?"
"No!"
"Then I can't see the sense in panicking," said Twoflower calmly.”

“If you do not know where you come from, then you don't know where you are, and if you don't know where you are, then you don't know where you're going. And if you don't know where you're going, you're probably going wrong.”

“It's not lying when you do it to officers!”

“Learnin’ how not to do things is as hard as learning how to do them.”

“Good or bad, do it as you. Too many lies and there's no truth to go back to.”

“You do know you could find yourself charged with being a dominant species while under the influence of impulse-driven consumerism, don't you?”

“Do you know how wizards like to be buried?"
"Yes!"
"Well, how?"
Granny Weatherwax paused at the bottom of the stairs.
"Reluctantly.”

“but what should we do when the highborn and wealthy take to crime? Indeed, if a poor man will spend a year in prison for stealing out of hunger, how high would the gallows need to be to hang the rich man who breaks the law out of greed?”

“FOR I CAN SEE THE BALANCE AND YOU HAVE LEFT THE WORLD MUCH BETTER THAN YOU FOUND IT, AND IF YOU ASK ME, said Death, NOBODY COULD DO ANY BETTER THAN THAT….”

“They obeyed, as wise men do when a woman puts her foot down…”

“Don't do anything I wouldn't do, if you ever find anything I wouldn't do.”

“It's hard to explain," said Brutha. "But I think it's got something to do with how people should behave… you should do things because they're right. Not because gods say so. They might say something different another time.”

“I don’t know what to do,” he said. “No harm in that. I’ve never known what to do,” said Rincewind with hollow cheerfulness. “Been completely at a loss my whole life.” He hesitated. “I think it’s called being human, or something.”

“Witches aren’t like that. We live in harmony with the great cycles of Nature, and do no harm to anyone, and it’s wicked of them to say we don’t. We ought to fill their bones with hot lead.”

“Questions don't have to make sense, Vincent," said Miss Susan. "But answers do.”

“Ach, people are always telling us not to do things" said Rob Anybody, "that's how we ken the most interesting things to do.”

“Oh, where are my manners? Do sit down. Pull up a small child.”