It's daft, locking us up," said Nanny. "I'd have had us killed."
"That's because you're basically good," said Magrat. "The good are innocent and create justice. The bad are guilty, which is why they invent mercy.

And just when you’d think [humans] were more malignant than ever Hell could be, they occasionally showed more grace than Heaven ever dreamed of.

Nanny's philosophy of life was to do what seemed like a good idea at the time, and do it as hard as possible. It had never let her down.

Hell wasn't a major reservoir of evil, any more then Heaven, in Crowley's opinion, was a fountain of goodness; they were just sides in the great cosmic chess game. Where you found the real McCoy, the real grace and the real heart-stopping evil, was right inside the human mind.

People couldn't become truly holy, he said, unless they also had the opportunity to be definitively wicked.

I believe you find life such a problem because you think there are good people and bad people. You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides.