It was a foolish question, and made Leithen cross. "He never went mad in your sense. My dear fellow, you're very much wrong if you think there was anything pathological about him--then. The man was brilliantly sane. His mind was as keen is a keen sword. I couldn't understand him, but I could judge of his sanity right enough." I asked if it made him happy or miserable. "At first I think it made him uncomfortable. He was restless because he knew too much and too little. The unknown pressed in on his mind as bad air weighs on the lungs. Then it lightened and he accepted the new world in the same sober practical way that he took other things. I think that the free exercise of his mind in a pure medium gave him a feeling of extraordinary power and ease. His eyes used to sparkle when he talked. And another odd thing he told me. He was a keen rockclimber, but, curiously enough, he had never a very good head. Dizzy heights always worried him, though he managed to keep hold on himself. But now all that had gone. The sense of the fulness of Space made him as happy--happier I believe--with his legs dangling into eternity, as sitting before his own study fire. "I remember saying that it was all rather like the mediaeval wizards who made their spells by means of numbers and figures. "He caught me up at once. 'Not numbers,' he said. "Number has no place in Nature. It is an invention of the human mind to atone for a bad memory. But figures are a different matter. All the mysteries of the world are in them, and the old magicians knew that at least, if they knew no more.' "He had only one grievance. He complained that it was terribly lonely. 'It is the Desolation,' he would quote, 'spoken of by Daniel the prophet.' He would spend hours travelling those eerie shifting corridors of Space with no hint of another human soul. How could there be? It was a world of pure reason, where human personality had no place. What puzzled me was why he should feel the absence of this. One wouldn't you know, in an intricate problem of geometry or a game of chess. I asked him, but he didn't understand the question. I puzzled over it a good deal, for it seemed to me that if Hollond felt lonely, there must be more in this world of his than we imagined. I began to wonder if there was any truth in fads like psychical research. Also, I was not so sure that he was as normal as I had thought: it looked as if his nerves might be going bad.