In the first case it must be subject to natural laws; in the second it must be operated, produced by some one possessing its secret. Everyone agreed that the phenomenon had appeared and disappeared repeatedly in the past, hence if it were a natural thing there was every reason to believe that it would continue to appear and vanish. If natural and controlled by nature’s forces, then the fact that it had ceased to exist just after I arrived was merely a coincidence. Moreover, if natural, and if it followed the ordinary and accepted laws of natural phenomena, there was every reason to expect that the periods of its existence and non-existence would be definite, well-established cycles. On the other hand, if it were a man-made and man-operated thing, it had unquestionably been cut off purposely as soon as I had passed over it, and its periods of existence in the past would have been, in all probability, irregular and erratic. I was surprised that I had not thought of making a systematic study of its past, but I would lose no time in doing so now. Neither the prince, nor Itza, nor the princesses could give me any definite information on the matter, but old Nohul Voh, I felt sure, would be able to help me. We had become very friendly, really chummy in fact, and he had long before cast aside his assumed shell of mystery, and had been remarkably frank with me in regard to his knowledge and his powers. Only on the matter of his Book of the Past and Book of the Future, as he called them, was he reticent. He would divulge nothing of this matter, but I had become convinced that this was because of his inability to explain it rather than because of disinclination. In fact, I firmly believed that--as I had thought in the beginning--it was some form of hypnotism, mental-telepathy or mind-reading, which was as much a mystery to him as to anyone else, but that rather than admit that he did not understand it, he pretended it was a secret he could not reveal. However, in all other matters he was frank with me. His mysterious sphere he had explained to the best of his ability, though even this was a mystery to him. Naturally he knew nothing of the atomic theory, of electrons, of ether waves, and hence he could not readily grasp the theory I had formulated to account for it. He had stumbled upon the force, had adapted it to his uses, and there he had stopped. It was the same with all his other knowledge and discoveries.