"That's why I pick apart why I care about people - and see if the patterns apply consistently - and apply my vivid imagination to various counterfactuals. There are occasional discontinuities. I couldn't guess except by reference to other people how something like - say - doing magic might affect me, before I did it. But if I have a sample of something I can take it apart. I guessed right about how much witchcraft practice it would take to develop noticeable dependence, after I'd tried two spells. I'm not doing statistics. I'm doing - clockwork. You don't have to take apart a hundred watches, you have to know what your gears do."