"The work of the philosophical policeman, is at once bolder and more subtle than that of the ordinary detective. The ordinary detective goes to pot-houses to arrest thieves; we go to artistic tea-parties to detect pessimists. The ordinary detective discovers from a ledger or a diary that a crime has been committed. We discover from a book of sonnets that a crime will be committed. We have to trace the origin of those dreadful thoughts that drive men on at last to intellectual fanaticism and intellectual crime."

G.K. Chesterton