"That was last October, the twenty-fourth, to be exact. Since then the thing has happened twice again. On each occasion I have had the same premonitory drowsiness. I have struggled against it, and it has mastered me at just the critical moment. The second time when I came to I was more badly hurt than before. My sister happened to be up early that morning, and there was no disguising my condition from her. She went off for Lennox. When he came he fixed me up and gave me a sleeping draught--which I didn't need--and I slept nearly the whole day. He held the opinion, which I wrested from him later, that I had had some sort of seizure, the result of overwork, and that I had inflicted the injuries on myself during unconsciousness. The rest he put down to hallucination. He was a fool, and I told him so. Whatever the thing was, it was no hallucination." "How wide was the skylight open?" "About eighteen inches." "Did you find any traces in the morning?" "Not a mark. The building is high, as you know, and the sides are of perfectly plain boarding. There is nothing that could give foothold, except to a monkey, and the nearest tree is eight feet off. Oh, I went over the whole ground carefully! Whatever it was that came, it did not reach me from the ground." I moved impatiently. "But what other way could it have reached you?" "That's what I ask myself," said Lessing grimly. "Do I look like a man subject to brain trouble?" "No," I said. "I gave that theory up almost immediately." "Then what do you make of it?" he asked quietly. "Make of it!" I cried. "Good heavens, man, do you realize that you're asking me to believe a thing that's outside the range of all human possibility!" "Human possibility! What is human possibility? I tell you the thing as it happened, simply." He rose and began to pace to and fro in the room. "I'm a sane man. I'm not given to imaginary things. And besides--you saw yourself----" "Wait a moment," I said. "About this light. Have you used the same lamp right along?" Lessing gave a quick look. I wondered if he had divined my visit to the laboratory that first morning. "No. I altered it after the second time. There was an interval of over four months when nothing happened at all. I tried to reason it all out, and I concluded that in some way the lamp had had to do with it. From the position of the building, and the woods about it, the light I was at first using could be visible only from one certain direction. I wanted to investigate the whole thing systematically, and with that idea I raised the lamp and fitted a strong reflector that would throw the light outside the building at will, and in any direction." His description corresponded with the light I had seen above the tree-tops, the night of Pete's adventure with the turkey-buzzard. "You were using this the last time?" "Yes. I had been experimenting with it, off and on, for several weeks."