"Each of these four cities was free and independent, each ruled by a council selected by its inhabitants. And being thus independent, there arose rivalry between the cities, and fierce jealousy. Each strove to outdo the others, in their scientific achievements, and each strove to keep its blood from intermixing with the others. Thus in the city of cylinders, the Kanlars, or people of the cylinders, gradually evolved into a bright-haired race, while in Kom, the Khluns, or people of the cones, were a dark-haired race. And the other two cities differed likewise from each other and the rest. "Ages passed, and then down from the north rolled a mighty tide of ice, sweeping over the whole land and submerging all under its frozen flood. It rolled down toward the four cities, and finally had forged south until it was at the gates of the city of cubes. In desperation, the people of the cubes appealed to those in Kom for shelter, and it was granted them. They came down to Kom, every one, and the ice rolled over and hid the city of cubes. Next it engulfed the city of spheres, and its people likewise found refuge in Kom, which was the most southern of all the four cities. And finally, the ice-tide swept over the city of cylinders, and its people, the Kanlars, were forced to seek refuge in Kom also, though they liked it not. "But the ice did not stop. It came on, ever south, until it threatened to cover Kom also, and leave our people homeless and shelterless. So, taking counsel among themselves, the people of Kom set out to stop the progress of the glacial sheet. "They kindled great uprisings far beneath the earth's surface, until the tortured earth heaved up in a great wall across the ice-flood's path. And then, that this wall of earth might not be swept away, the scientists of Kom showed them a way by which every kind of material could be transmuted at will into other elements, by a recasting of its electronic structure. And, using this power, the people of Kom smoothed the gigantic barrier they had created, and then, using the instruments their scientists had devised for them, they turned on the great wall a ray that changed it to metal by its power of element-transmutation. It was finished, and when the ice rolled down to this smooth mountain-range of metal, it was checked, halted. Far away, on either side, it rolled on and engulfed the country, but the wall so dammed it that it could not progress farther toward the city. "Yet the cold of the glacier was not halted by the wall, and to combat that cold, the great shield of force was devised that stretches over all Kom, and into which you crashed in your car. It admitted the sun's light and heat, but excluded the cold winds from the glacier. And thus, having thwarted nature itself, the troubles of the people of Kom were seemingly at an end.