Phrenology, as everyone knows, is a way of reading someone’s character, aptitude, and abilities by examining the bumps and hollows on their head. Therefore–according to the kind of logical thinking that characterises the Ankh-Morpork mind–it should be possible to mould someone’s character by giving them carefully graded bumps in all the right places. You can go into a shop and order an artistic temperament with a tendency to introspection and a side order of hysteria. What you actually get is hit on the head with a selection of different size mallets, but it creates employment and keeps the money in circulation, and that’s the main thing.
— Terry Pratchett, Men at Arms