'Why are our people going out there?' said Mr Boggis of the Thieves' Guild.
'Because they are showing a brisk pioneering spirit and seeking wealth and... additional wealth in a new land,' said Lord Vetinari.
'What's in it for the Klatchians?' said Lord Downey.
'Oh, they've gone out there because they are a bunch of unprincipled opportunists always ready to grab something for nothing,' said Lord Vetinari. [...] The Patrician looked down again at his notes. 'Oh, I do beg your pardon,' he said. 'I seem to have read those last two sentences in the wrong order.
[p. 24, 25]
'Can't argue with the truth, sir.'
'In my experience, Vimes, you can argue with anything.'
[p. 92, Vimes and Vetinari, submitted by Kimberley Beattie]
'Detectoring is like gambling,' said Vimes, putting down the clove. 'The secret is to know the winner in advance.'
'And trust no-- Trust practically no-one. All right? Except trustworthy people.'
[p. 107, Vimes]
One of the universal rules of happiness is: always be wary of any helpful item that weighs less than its operating manual.
[p. 178, footnote]
'I'm just going to kick some arse dear'
'Oh, good. Just be sure you wrap up well, then.' [pg 182 - Vimes and Lady Sybil; submitted by Kimberley Beattie]
'My strength is like the strength of ten because my heart is pure,' said Carrot.
'Really? Well, there's eleven of them.'
Someone's behind this. Someone wants to see a war. [...] I've got to remember that. This isn't a war. This is a crime.
'It is always useful to face an enemy who is prepared to die for his country,' he read. 'This means that both you and he have exactly the same aim in mind.'
[p. 207, from "Veni, Vidi, Vici" by general Tacticus]
'We'll all be killed.'
'Think of it as the lesser of two evils.'
'What's the other one?'
Vimes drew his sword.
The night is always old. He'd walked too often down dark streets in the secret hours and felt the night stretching away, and known in his blood that while days and kings and empires come and go, the night is always the same age, always aeons deep. Terrors unfolded in the velvet shadows and while the nature of the talons may change, the nature of the beast does not.
'And I promise you this,' he [Carrot] shouted, 'if we succeed, no-one will remember. And if we fail, no one will forget!'
'A man like that could inspire a handful of broken men to conquer a country.'
'Fine. Just so long as he does it on his day off.'
[p. 379, Ahmed and Vimes]