They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance.

He felt that the darkness was full of unimaginable horrors - and the trouble with unimaginable horrors was that they were only too easy to imagine.

I would like permission to fetch a note from my mother, sir' Ridcully sighed. 'Rincewind, you once informed me, to my everlasting puzzlement, that you never knew your mother because she ran away before you were born. Distinctly remember writing it down in my diary. Would you like another try?' 'Permission to go and find my mother?'

I don’t think it's weak to admit you made a mistake. That takes strength, if you ask me.

It's not worth doing something unless you were doing something that someone, somewere, would much rather you weren't doing.

Them as can do has to do for them as can't. And someone has to speak up for them as has no voices.

Look, he said to his imagination, if this is how you're going to behave, I shan't bring you again.