Read the excerpt from The Strange Case of Dr. Jekyll and Mr. Hyde. "Sir,” said the butler, turning to a sort of mottled pallor, "that thing was not my master, and there’s the truth. My master”—here he looked round him and began to whisper—"is a tall, fine build of a man, and this was more of a dwarf.” Utterson attempted to protest. "O, sir,” cried Poole, "do you think I do not know my master after twenty years? Do you think I do not know where his head comes to in the cabinet door, where I saw him every morning of my life? No, sir, that thing in the mask was never Dr. Jekyll—God knows what it was, but it was never Dr. Jekyll; and it is the belief of my heart that there was murder done.” Which theme does this passage best support?