"We will soon know if the first way is still open," he said quietly.

             Alvin jumped from his chair, scattering maps in all directions.

             "Where is it?" he cried eagerly.

             Rorden laughed and pushed him back into his seat.

             "I haven't kept you waiting all this time because I wanted to," he said. "It's true that you were too young to leave Diaspar before, even if we knew how it could be done. But that's not the only reason why you had to wait. The day you came to see me, I set the machines searching through the records to discover if anyone after Alaine's time had tried to leave the city. I thought you might not be the first, and I was right. There have been many others: the last was about fifteen million years ago. They've all been very careful to leave us no clues, and I can see Alaine's influence there. In his message he

             Stressed that only those who searched for themselves should be allowed to find the way, so I've had to explore many blind avenues. I knew that the secret had been hidden carefully—yet not so carefully that it couldn't be found.

             "About a year ago I began to concentrate on the idea of transport. It was obvious that Diaspar must have had many links with the rest of the world, and although the Port itself has been buried by the desert for ages, I thought that there might be other means of travel. Right at the beginning I found that the Associators would not answer direct questions: Alaine must have put a block on them just as I once did for your benefit. Unfortunately I can't remove Alaine's block, so I've had to use indirect methods.

             "If there was an external transport system, there's certainly no trace of it now. Therefore, if it existed at all, it has been deliberately concealed. I set the Associators to investigate all the major engineering operations carried out in the city since the records began. This is a report on the construction of the central park— and Alaine has added a note to it himself. As soon as it encountered his name, of course, the machine knew it had finished the search and called for me.

             Rorden glanced at the paper as if rereading part of it again. Then he continued:

             "We've always taken it for granted that all the moving ways should converge on the Park: it seems natural for them to do so. But this report states that the Park was built after the founding of the city—many millions of years later, in fact. Therefore the moving ways once led to something else. "

             "An airport, perhaps?"

             "No: flying was never allowed over any city, except in very ancient times, before the moving ways were built. Even Diaspar is not as old as that! But listen to Alaine's note:

             " 'When the desert buried the Port of Diaspar, the emergency system which had been built against that day was able to carry the remaining transport. It was finally closed down by Yarlan Zey, builder of the Park, having remained almost unused since the Migration.' "

             Alvin looked rather puzzled.

             "It doesn't tell me a great deal," he complained.

             Rorden smiled. "You've been letting the Associators do too much thinking for you," he admonished gently. "Like all of Alaine's statements, it's deliberately obscure lest the wrong people should learn from it. But I think it tells us quite enough. Doesn't the name 'Yarlan Zey' mean anything to you?"

             "I think I understand," said Alvin slowly. "You're talking about the Monument?"

             "Yes: it's in the exact center of the Park. If you extended the moving ways, they would all meet there. Perhaps, once upon a time, they did. "

             Alvin was already on his feet.

             "Let's go and have a look," he exclaimed.

             Rorden shook his head.

             "You've seen the Tomb of Yarlan Zey a score of times and noticed nothing unusual about it. Before we rush off, don't you think it would be a good idea to question the machines again?"

             Alvin was forced to agree, and while they were waiting began to read the report that the Associator had already produced.

             "Rorden," he said at last, "what did Alaine mean when he spoke about the Migration?"

             "It's a term often used in the very earliest records," answered Rorden. "It refers to the time when the other cities were decaying and all the human race was moving towards Diaspar."

             "Then this 'emergency system,' whatever it is, leads to them?"

             "Almost certainly."

             Alvin meditated for a while.

             "So you think that even if we do find the system, it will only lead to a lot of ruined cities?"

             "I doubt if it will even do that," replied Rorden. "When they were abandoned, the machines were closed down and the desert will have covered them by now."

             Alvin refused to be discouraged.

             "But Alaine must have known that!" he protested. Rorden shrugged his shoulders.

             "We're only guessing," he said, "and the Associator hasn't any information at the moment. It may take several hours, but with such a restricted subject we should have all the recorded facts before the end of the day. We'll follow your advice after all."

             The screens of the city were down and the sun was shining fiercely, though its rays would have felt strangely weak to a man of the Dawn Ages. Alvin had made this journey a hundred times before, yet now it seemed almost a new adventure. When they came to the end of the moving way, he bent down and examined the surface that had carried them through the city. For the first time in his life, he began to realize something of its wonder. Here it was motionless, yet a hundred yards away it was rushing directly towards him faster than a man could run.

             Rorden was watching him, but he misunderstood the boy's curiosity.

             "When the Park was built," he said, "I suppose they had to remove the last section of the way. I doubt if you'll learn anything from it."

             "I wasn't thinking of that," said Alvin. "I was wondering how the moving ways work."

             Rorden looked astonished, for the thought had never occurred to him. Ever since man had lived in cities, they had accepted without thinking the multitudinous services that lay beneath their feet. And when the cities had become completely automatic, they had ceased even to notice that they were there.

             "Don't worry about that, " he said. "I can show you a thousand greater puzzles. Tell me how my Recorders get their information, for example."

             So, without a second thought, Rorden dismissed the moving ways—one of the greatest triumphs of human engineering. The long ages of research that had gone to the making of anisotropic matter meant nothing to him. Had he been told that a substance could have the properties of a solid in one dimension and of a liquid in the other two, he would not even have registered surprise.

             The Park was almost three miles across, and since every pathway was a curve of some kind all distances were considerably exaggerated. When he had been younger Alvin had spent a great deal of time among the trees and plants of this largest of the city's open spaces. He had explored the whole of it at one time or another, but in later years much of its charm had vanished. Now he understood why: he had seen the ancient records and knew that the Park was only a pale shadow of a beauty that had vanished from the world.