A Hat Full of Sky (Discworld, #32)

by Terry Pratchett

It was too easy to slip into careless little cruelties because you had power and other people hadn’t, too easy to think other people didn’t matter much, too easy to think that ideas like right and wrong didn’t apply to you. At the end of that road was you dribbling and cackling to yourself all alone in a gingerbread house, growing warts on your nose. Witches needed to know other witches were watching them.