" Virtually every man has enemies. Sometimes they’re business enemies. More often they’re personal enemies, people who hate him, people who will look down their noses and say it’s too bad when they hear he’s bumped off, but who will be tickled to death just the same; but it takes a peculiar psychological build-up to perpetrate a murder. A man must have a certain innate ferocity, a certain lack of consideration, and, usually, a lack of imagination.” “Why a lack of imagination?” “I don’t know,” he said, “except that it’s nearly always true. I think imaginative people sympathize with the sufferings of others because they’re able to visualize those sufferings more keenly in their own minds. An unimaginative person, on the other hand, can’t visualize himself in the shoes of another. Therefore, he sees life only from his own selfish angle. Killers are frequently cunning, but they’re rarely original. They’re selfish, and usually determined. Of course, I’m not talking now about a murder which is the result of some sudden overpowering emotion. "
― Erle Stanley Gardner , The Case of the Lame Canary (Perry Mason, #11)