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

William: "I'm sure we can all pull together, sir." Vetinari: "Oh, I do hope not. Pulling together is the aim of despotism and tyranny. Free men pull in all kinds of directions.

I've often felt depressed; everyone feels depressed.

The people of Ankh-Morpork had a straightforward, no-nonsense approach to entertainment, and while they were looking forward to seeing a dragon slain, they'd be happy to settle instead for seeing someone being baked alive in his own armour. You didn't get the chance every day to see someone baked alive in their own armour. It would be something for the children to remember.

Good and bad is tricky," she said. "I ain't too certain about where people stand. P'raps what matters is which way you face." (pp. 348-349)

Do you not know that a man is not dead while his name is still spoken?

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