Syme's eyes were bright with a sympathetic curiosity.
"What do you do, then?" he said.
"The work of the philosophical policeman," replied the man in blue, "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."
G.K. Chesteron, The Man Who Was Thursday.