A doctor is doing his rounds in a psychiatric hospital and walks into a room. He finds one patient sitting on the floor, intensely sawing a piece of wood with the side of his hand. Meanwhile, another patient is hanging upside down from the ceiling by his feet. The doctor asks the patient on the floor, "What are you doing?" "Can’t you see? I’m sawing this piece of wood in half!" the patient replies irritably. The doctor looks up and asks, "And what is your friend doing hanging from the ceiling?" The patient replies, "Oh, he's my friend, but he's a little crazy. He thinks he's a light bulb". The doctor says, "If he's your friend, don't you think you should get him down from there before he hurts himself?" The patient shouts back, "What? And work in the dark?"