“This, Monsieur,” he said, “is a spike which perfectly fits a hole still to be seen in the cornice supporting the terrace. Larsan, who thought and prepared for everything in case of any emergency, had fixed this spike into the cornice. All he had to do to make his escape good was to plant one foot on a stone which is placed at the corner of the château, another on this support, one hand on the cornice of the keeper’s door and the other on the terrace, and Larsan was clear of the ground. The rest was easy. His acting after dinner as if he had been drugged was make believe. He was not drugged; but he did drug me. Of course he had to make it appear as if he also had been drugged so that no suspicion should fall on him for my condition. Had I not been thus overpowered, Larsan would never have entered Mademoiselle Stangerson’s chamber that night, and the attack on her would not have taken place.” A groan came from Darzac, who appeared to be unable to control his suffering. “You can understand,” added Rouletabille, “that Larsan would feel himself hampered from the fact that my room was so close to his, and from a suspicion that I would be on the watch that night. Naturally, he could not for a moment believe that I suspected _him_! But I might see him leaving his room when he was about to go to Mademoiselle Stangerson. He waited till I was asleep, and my friend Sainclair was busy trying to rouse me. Ten minutes after that Mademoiselle was calling out, ‘Murder!’” “How did you come to suspect Larsan?” asked the President. “My pure reason pointed to him. That was why I watched him. But I did not foresee the drugging. He is very cunning. Yes, my pure reason pointed to him; but I required tangible proof so that my eyes could see him as my pure reason saw him.” “What do you mean by your pure reason?” “That power of one’s mind which admits of no disturbing elements to a conclusion. The day following the incident of ‘the inexplicable gallery,’ I felt myself losing control of it. I had allowed myself to be diverted by fallacious evidence; but I recovered and again took hold of the right end. I satisfied myself that the murderer could not have left the gallery, either naturally or supernaturally. I narrowed the field of consideration to that small circle, so to speak. The murderer could not be outside that circle. Now who were in it? There was, first, the murderer. Then there were Daddy Jacques, Monsieur Stangerson, Frédéric Larsan, and myself. Five persons in all, counting in the murderer. And yet, in the gallery, there were but four. Now since it had been demonstrated to me that the fifth could not have escaped, it was evident that one of the four present in the gallery must be a double—he must be himself and the murderer also. Why had I not seen this before? Simply because the phenomenon of the double personality had not occurred before in this inquiry.