"Not this one," replied Crusoe. "Perhaps the original Professor did find me wandering around alone. But then my friend here came searching for me, and after studying his characteristics for a time, killed him and took his place. He's a great mimic, is my friend. That, in fact, is why I was sent to get him, and was bringing him, a prisoner, back to his home planet. He's mimicked all sorts of people, even those who have only the slightest resemblance to humanoids. It was nothing at all for him to become a Professor. Physically, of course, he probably doesn't fit the part too well. Do you mean to say that you haven't noticed?" The Professor laughed gently. "Angel wouldn't notice. Haven't you realized yet that he's half blind? He stumbles, blunders into things. He can't see well. He didn't notice the difference. Not when I acted so well." * * * * * Angel sought escape from confusion in a fact he could understand. He said pathetically, "You killed the real Professor? He was a guy who wouldn't have hurt anybody. You killed him?" "Of course. I've killed much better and more important people than he would ever be." "He's right, Angel, he's an experienced killer. But all his killing won't help him now. He needs me to open and operate the ship. And I'm not cooperating." Angel held fast to what he could understand. He muttered to himself, "The dirty killer. The rat." The little man ignored him. He said, "You were very wise, Tlaxon--you remember your name now?--you were very wise, when you saw that a crash threatened, to lock the ship's machinery so that only your own personal characteristic motions would open it again. That was too much for even me to mimic. Your cleverness left me helpless to escape from the planet without you. After we finally crashed, and I recovered from the shock, I examined the ship's machinery. There seemed to be no serious damage. But I couldn't operate it. I needed your help. And you were unconscious. Sitting at the controls, you had received a much more severe shock than I had. You didn't recover for many hours. And after you did, you remembered nothing. You were still unable to be of use to me. "I was enraged, but there was nothing I could do. I tried to keep you in the ship, but once, while I was asleep, you awoke and stumbled out. I had no choice then but to follow you in order to protect you. The ship locked automatically behind me, leaving me worse off than ever. But I had to follow because my escape depended on your own. It was then that Professor discovered you and I discovered him. I had to kill him. I think you can see why." "Yes, I see now."