"'How if Space is really full of things we cannot see and as yet do not know? How if all animals and some savages have a cell in their brain or a nerve which responds to the invisible world? How if all Space be full of these landmarks, not material in our sense, but quite real? A dog barks at nothing, a wild beast makes an aimless circuit. Why? Perhaps because Space is made up of corridors and alleys, ways to travel and things to shun? For all we know, to a greater intelligence than ours the top of Mont Blanc may be as crowded as Piccadilly Circus.' "But at that point I fell asleep and left Hollond to repeat his questions to a guide who knew no English and a snoring porter. "Six months later, one foggy January afternoon, Hollond rang me up at the Temple and proposed to come to see me that night after dinner. I thought he wanted to talk Alpine shop, but he turned up in Duke Street about nine with a kit-bag full of papers. He was an odd fellow to look at--a yellowish face with the skin stretched tight on the cheek-bones, clean-shaven, a sharp chin which he kept poking forward, and deep-set, greyish eyes. He was a hard fellow, too, always in pretty good condition, which was remarkable considering how he slaved for nine months out of the twelve. He had a quiet, slow-spoken manner, but that night I saw that he was considerably excited. "He said that he had come to me because we were old friends. He proposed to tell me a tremendous secret. 'I must get another mind to work on it or I'll go crazy. I don't want a scientist. I want a plain man.' "Then he fixed me with a look like a tragic actor's. 'Do you remember that talk we had in August at Chamonix--about Space? I daresay you thought I was playing the fool. So I was in a sense, but I was feeling my way towards something which has been in my mind for ten years. Now I have got it, and you must hear about it. You may take my word that it's a pretty startling discovery.' "I lit a pipe and told him to go ahead, warning him that I knew about as much science as the dustman. "I am bound to say that it took me a long time to understand what he meant. He began by saying that everybody thought of Space as an 'empty homogeneous medium.' 'Never mind at present what the ultimate constituents of that medium are. We take it as a finished product, and we think of it as mere extension, something without any quality at all. That is the view of civilised man. You will find all the philosophers taking it for granted. Yes, but every living thing does not take that view. An animal, for instance. It feels a kind of quality in Space. It can find its way over new country, because it perceives certain landmarks, not necessarily material, but perceptible, or if you like intelligible. Take an Australian savage. He has the same power, and, I believe, for the same reason. He is conscious of intelligible landmarks.' "'You mean what people call a sense of direction,' I put in.