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

“Some humans would do anything to see if it was possible to do it. If you put a large switch in some cave somewhere, with a sign on it saying 'End-of-the-World Switch. PLEASE DO NOT TOUCH', the paint wouldn't even have time to dry.”

“Did I do anything last night that suggested I was sane?”

“Talent just defines what you do...It doesn't define what you are. Deep down, I mean. When you know what you are, you can do anything”

“Everyone says it's going to be Snapcase at the palace. He listens to the people.""Yeah, right," said Vimes. And I listen to the thunder. But I don't do anything about it.”

“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.”

“Preston, I don't think this creature could ever find its way into your head. Quite apart from anything else, it seems pretty crowded and complicated to me.”