"Down!" said Gor with unconscious dramatic effect, and he pointed at the rocky floor of the cave. "I have gone where even the Beast of the North cannot go. The caves back of this you have seen, but only Gor has seen the hole--the hole where a strong man can climb down; a hole too small for the great beast to get through. Gor has gone down to find more caves below and more caves below them. "Far down is a place where it is always warm. There is water in lakes and streams. Gor has caught fish in that water, and they were good. There are growing things like the round earth-plants that come in the night, and they, too, were good. "Will you follow Gor?" he demanded. "And when the Beast is gone and the Sun-god comes back we will return--" * * * * * The blast that found its way inside the cave furnished its own answer; the echoing, "We follow! We follow!" spoken through chattering teeth was not needed. The women of the tribe shivered more from the cold than from fear as they gathered together their belongings, their furs and hides and crude stone implements; and the shambling man-shape, called Gor, led them to the hole down which a strong man might climb, led them down and still down.... But, as to the rest--Gor's promise of safe return to the light of day and that outer world where the Sun-god shone--how was Gor to know that a mighty glacier would lock the whole land in ice for endless years, and, retreating, leave their upper caves filled and buried under a valley heaped with granite rocks? Even had the way been open to the land above, Gor himself could never have known when that ice-sheet left. For when that day came and once more the Sun-god drew steamy spirals from the drenched and thawing ground, Gor, deep down in the earth, had been dead for countless years. Only the remote descendants of that earlier tribe now lived in their subterranean home, though even with them there were some who spoke at times of those legends of another world which their ancestors had left. And through the long centuries, while evolution worked its slow changes, they knew nothing of the vanishing ice, of the sun and the gushing waters, the grass and forests that came to cover the earth. Nor did their descendants, exploring interminable caves, learning to tame the internal fires, always evolving, always growing, have any remote conception of a people who sailed strange seas to find new lands and live and multiply and build up a country of sky-reaching cities and peaceful farmlands, of sunlit valleys and hills. But always there were adventurous souls who made their way deeper and deeper into the earth; and among them in every generation was one named Gor who was taught the tribal legends and who led the adventurers on. But legends have a trick of changing, and instead of searching upward, it was through the deeper strata that they made their slow way in their search for a mystic god and the land of their fathers' fathers....