They had come up to watch the rising of the sun: that sun which they had never seen except as an orb of blackness, occluding the zodiacal stars in its course from horizon to horizon.ExcerptRodis and Hilar had climbed from their natal caverns to the top chamber of the high observatory tower. Pressed close together, for warmth as well as love, they stood at an eastern window looking forth on hills and valleys dim with perennial starlight. They had come up to watch the rising of the sun: that sun which they had never seen except as an orb of blackness, occluding the zodiacal stars in its course from horizon to horizon.Thus their ancestors had seen it for millenniums. By some freak of cosmic law, unforeseen, and inexplicable to astronomers and physicists, the sun's cooling had been comparatively sudden, and the earth had not suffered the long-drawn complete desiccation of such planets as Mercury and Mars. Rivers, lakes, seas, had frozen solid; and the air itself had congealed, all in a term of years historic rather than geologic. Millions of the earth's inhabitants had perished, trapped by the glacial ice, the centigrade cold. The rest, armed with all the resources of science, had found time to entrench themselves against the cosmic night in a world of ramified caverns, dug by atomic excavators far below the surface.Here, by the light of artificial orbs, and the heat drawn from the planet's still-molten depths, life went on much as it had done in the outer world. Trees, fruits, grasses, grains, vegetables, were grown in isotope-stimulated soil or hydroroponic gardens, affording food, renewing a breathable atmosphere. Domestic animals were kept; and birds flew; and insects crawled or fluttered. The rays considered necessary for life and health were afforded by the sunbright lamps that shone eternally in all the caverns.Little of the old science was lost; but, on the other hand, there was now little advance. Existence had become the conserving of a fire menaced by inexorable night. Generation by generation a mysterious sterility had lessened the numbers of the race from millions to a few thousands. As time went on, a similar sterility began to affect animals; and even plants no longer flourished with their first abundance. No biologist could determine the cause with certainty.Perhaps man, as well as other terrestrial life-forms, was past his crime, and had begun to undergo collectively the inevitable senility that comes to the individual. Or perhaps, having been a surface-dweller throughout most of his evolution, he was inadaptable to the cribbed and prisoned life, the caverned light and air; and was dying slowly from the deprivation of things he had almost forgotten.