"It's witchcraft with all the crusts cut off, and real witchcraft is ALL crusts."

"It's rude to stare," said the troll. Its mouth opened with a little crest of foam, and shut again in exactly the same way that water closes over a stone. "Is it? Why?" asked Rincewind. How does he hold himself together, his mind screamed at him. Why doesn't he spill?"

"She heard him mutter, 'Can you take away this grief?''I'm sorry,' she replied. 'Everyone asks me. And I would not do so even if I knew how. It belongs to you. Only time and tears take away grief; that is what they are for."

"But can’t you just wave your hand and make all the dirt fly away, then?" [...]"That works, but only if you wave them about on the floor with a scrubbing brush."

"There are thousands of good reasons why magic doesn't rule the world. They're called Witches and Wizards."

"That's what I don't like about magic. It does everything by magic."