"But something happened, some catastrophe. I can't imagine what it could be, but it must have happened. While it would be interesting to know the cause, all we can know is the effect. Travel ceased, and as time went by the colonies, which were probably rather small to begin with, lost their civilization. The colonies must have been rather dependent upon supplies shipped to them, and they must have had a limited number of highly trained scientists and specialists among them. Anyway, whatever the reason, they relapsed into savagery. And it was not until ages had passed that some of these colonies, utterly without memory of their glorious heritage, except perhaps disguised in myth and legend, attained a high technology again. Others stayed in savagery; some, like your world, Grizquetr, are in the transition stage. Your culture is roughly analogous to the ones that existed on Earth between 100 A.D. and 1000 A.D. Those dates mean nothing to you, I know, but let me assure you that we present-day Terrestrials regard those times as being, well, rather hazardous and, uh, unreasonable in their conduct." "I only half-understand you," replied the boy. "But didn't you say that nothing of the wisdom of the ancients survived on your planet? Well, why had it done so on ours? These islands must be the work of the old ones." "Correct! And that's not all. So is the Xurdimur itself." "What?" "Yes, it's obvious to me that this planet must once have been a tremendous clearing-house and landing field for spacecraft. These plains couldn't be natural; they must have been leveled out by machinery. A laboratory-born grass was planted that had all the characteristics needed to hold the soil together and keep erosion away. Plus the fact that the islands themselves were, you might say, caretakers, and kept the whole field spruced up. "Gods! I can imagine what a traffic this planet must have had to build such a landing-field! Ten thousand miles across! The mind boggles before the thought. They must have done things on a big scale then. Which makes it all the more difficult to figure out how they could have come to ruin. Will we ever know what force wrecked them?" Grizquetr, of course, had even less of an answer than Green. Both were silent for a while; then they cried out simultaneously when the pointed tips of the white towers surrounding Estorya glittered upon the horizon. One of the screens began flashing a series of cone shapes that indicated the towers. "If the island were still on automatic it would be forced to go around the entire nation," said Green. "But I'm running it now, and we're paying no attention to those towers." "Knock 'em down!" "That's just what I intend to do. But not right now. Let's see. Wonder how high we can go. Only one way to find out. Upsydaisy!" He pulled back the lever and the island began rising, though still maintaining its horizontal attitude.