“And it runs mechanically over its great course as regularly as clock-work.” “More accurately, I assure you, but there probably never was a greater mathematical problem than they solved in deciding on the size the sun should be and amount of light necessary to fill up all the recesses of the great vacancy. It was all very crude at the start; for years a great electric light was simply suspended in the centre of the cavern's roof and the light did not vary in color. A son of the first king suggested the plan of giving the sun diurnal movement and the changing light. The moon and stars were a later development. They found, too, that the light could not be made to reach certain recesses in the cavern where the roof approached the earth, so they finally built a great wall to keep the inhabitants within proscribed boundaries, and to prevent them from understanding the machinery of the heavens.” “Wonderful!” exclaimed Thorndyke. “But the temperature of the atmosphere, how does that happen to be so delightful and beneficial?” “I believe they do not themselves thoroughly comprehend that. The heat comes from the internal fires, and the fresh air from without in some mysterious way. At first, in a few places, the heat was too severe, but the scientific men among the first settlers obviated this difficulty by closing up the hottest of the fissures and opening others in the cooler parts of the cavern.” “And the people, where did they come from?” “From all parts of the earth. We had agents outside who selected such men and women that were willing to come, and who filled all the requirements, mentally and physically.” “But why do they desire to live here instead of out in the world, when they have all the wealth that they need to assure every advantage.” “They dread death, and it is undoubtedly true that life is prolonged here; our medical men declare that the longevity of every generation is improved.” “Is it possible? But tell me about the sun, when it sets, what becomes of it?” “It goes back to its place of rising through a great tunnel beneath us.” Thorndyke sat in deep thought for a moment; then he looked so steadily and so admiringly into Bernardino's eyes that she grew red with confusion. “But you, yourself, are you thoroughly content here?” “I know nothing else,” she continued. “I have heard little about your world except that your people are discontented, weak and insane, and that your changeable weather and your careless laws regarding marriage and heredity produce perpetual and innumerable diseases; that your people are not well developed and beautiful; that you war with one another, and that one tears down what another builds. I have, too, always been happy, and since you came I am happier still. I don't know what it means. I have never been so much interested in any one before.”