“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.
“Now who of the four persons in the gallery was both that person and the assassin? I went over in my mind what I had seen. I had seen at one and the same time, Monsieur Stangerson and the murderer, Daddy Jacques and the murderer, myself and the murderer; so that the murderer, then, could not be either Monsieur Stangerson, Daddy Jacques, or myself. Had I seen Frédéric Larsan and the murderer at the same time?—No!—Two seconds had passed, during which I lost sight of the murderer; for, as I have noted in my papers, he arrived two seconds before Monsieur Stangerson, Daddy Jacques, and myself at the meeting-point of the two galleries. That would have given Larsan time to go through the ‘off-turning’ gallery, snatch off his false beard, return, and hurry with us as if, like us, in pursuit of the murderer. I was sure now I had got hold of the right end in my reasoning. With Frédéric Larsan was now always associated, in my mind, the personality of the unknown of whom I was in pursuit—the murderer, in other words.
“That revelation staggered me. I tried to regain my balance by going over the evidences previously traced, but which had diverted my mind and led me away from Frédéric Larsan. What were these evidences?
“1st. I had seen the unknown in Mademoiselle Stangerson’s chamber. On going to Frédéric Larsan’s room, I had found Larsan sound asleep.
“2nd. The ladder.
“3rd. I had placed Frédéric Larsan at the end of the ‘off-turning’ gallery and had told him that I would rush into Mademoiselle Stangerson’s room to try to capture the murderer. Then I returned to Mademoiselle Stangerson’s chamber where I had seen the unknown.
“The first evidence did not disturb me much. It is likely that, when I descended from my ladder, after having seen the unknown in Mademoiselle Stangerson’s chamber, Larsan had already finished what he was doing there. Then, while I was re-entering the château, Larsan went back to his own room and, undressing himself, went to sleep.
“Nor did the second evidence trouble me. If Larsan were the murderer, he could have no use for a ladder; but the ladder might have been placed there to give an appearance to the murderer’s entrance from without the château; especially as Larsan had accused Darzac and Darzac was not in the château that night. Further, the ladder might have been placed there to facilitate Larsan’s flight in case of absolute necessity.