"Tyffany wondered if the witch could read minds.
'Minds? No,' said Mistress Weatherwax, climbing onto her broomstick. 'Faces, yes. Come here, young lady.'
Tiffany obeyed.
'The thing about witchcraft,' said Mistress Weatherwax, 'is that it's not like school at all. First you get the test, and then afterwards you spend years findin' out how you passed it. It's a bit like life in that respect.' "

Terry Pratchett, "The Wee Free Men"