" When a human doctor, after much bleeding and cupping, finds that a patient has died out of sheer desperation, he can always say, "Dear me, will of the gods, that will be thirty dollars please," and walk away a free man. This is because human beings are not, technically, worth anything. A good racehorse, on the other hand, may be worth twenty thousand dollars. A doctor who lets one hurry off too soon to that great paddock in the sky may well expect to hear, out of some dark alley, a voice saying something on the lines of "Mr. Chrysoprase is very upset," and find the brief remainder of his life full of incident. "

― Terry Pratchett , Feet of Clay (Discworld, #19; City Watch, #3)