"Yes, I think that's about right. And now, suppose that such a being became endowed with the natural senses, one by one. It would go through all the processes of the physical and mental evolution of humanity until it reached the highest of human attributes--the ability to think, and therefore to reason. In other words, from a merely living organism it would, in the old Scriptural language, have become a living soul. That is, obviously, what the words in Genesis were really intended to mean. It would then become capable of development, of proceeding from the partly-known to the more fully known, until, granted perfect physical and mental health, it reached what are generally called the limits of human knowledge." The Professor's thumb and finger went up to his chin again. He walked another two or three hundred yards in silence; then he recommenced his spoken argument with himself: "Limits of human knowledge? Yes, that sounds all very well in ordinary language, but are there any? Who was it said that a man trying to reach those limits was like the child who saw a rainbow for the first time, and started out to find the place where it rested? The simile is not bad, not by any means. Just in the same way, we try to imagine the limits of time and space, and we can't do it. Only infinity of space and duration are possible, and yet we can't grasp them; still, they are the only possible states in which we can exist. And now, as I have had a glimpse of the past, I wonder what this place would be like in ten thousand years? "Good heavens, how cold it is!" He shivered, and buttoned up his coat, and continued, looking about him on the vast snow-field dotted with hummocks of ice which lay bleak and lifeless about him: "Ah, I suppose either the Gulf Stream has got diverted, or the earth's axis has shifted and we are in another glacial epoch. "WE!" Again the shock of utter isolation struck him, but it seemed to hit him harder this time. The world that he had been born in lay ten thousand years behind him. For all he knew, he might be standing upon what was now the earth's North Pole. Civilisation, as he had known it, might have been wiped off the face of the earth, and the remnants of humanity flung back into savagery. He looked up at the sun, and saw that it was almost exactly where it had been, and that it had not perceptibly diminished in power. The idea was not at all pleasant to him, and very naturally his thoughts turned back once more to his cosy home that had been on the edge of Wimbledon Common ten thousand years ago. He remembered, with a curious sort of thrill, some notes which he had to complete that morning for his lecture--and in the same instant he was walking back across the turf towards his house through the warm May sunshine.