Rorden paused, and smiled a little ruefully.

             "There are other paradoxes that have not yet been resolved, but the problem is one for the psychologist rather than the historian. Even my records cannot be wholly trusted, and bear clear evidence of tampering in the very remote past.

             "Only Diaspar and Lys survived the period of decadence—Diaspar thanks to the perfection of its machines, Lys owing to its partial isolation and the unusual intellectual powers of its people. But both cultures, even when they had struggled back to their former level, were distorted by the fears and myths they had inherited.

             "Those fears need haunt us no longer. All down the ages, we have now discovered, there were men who rebelled against them and maintained a tenuous link between Diaspar and Lys. Now the last barriers can be swept aside and our two races can move together into the future—whatever it may bring."

             "I wonder what Yarlan Zey would think of this?" said Rorden thoughtfully. "I doubt if he would approve."

             The Park had changed considerably, so far very much for the worse. But when the rubble had been cleared away, the road to Lys would be open for all to follow.

             "I don't know," Alvin replied. "Though he closed the moving ways, he didn't destroy them as he might very well have done. One day we must discover the whole story behind the Park—and behind Alaine of Lyndar."

             "I'm afraid these things will have to wait," said Rorden, "until more important problems have been settled. In any case, I can picture Alaine's mind rather well: once we must have had a good deal in common."

             They walked in silence for a few hundred yards, following the edge of the great excavation. The Tomb of Yarlan Zey was now poised on the brink of a chasm, at the bottom of which scores of robots were working furiously.

             "By the way," said Alvin abruptly, "did you know that Jeserac is staying in Lys? Jeserac, of all people! He likes it there and won't come back. Of course, that will leave a vacancy on the Council."

             "So it will," replied Rorden, as if he had never given the matter any thought. A short time ago he could have imagined very few things more unlikely than a seat on the Council; now it was probably only a matter of time. There would, he reflected, be a good many other resignations in the near future. Several of the older councillors had found themselves unable to face the new problems pouring upon them.

             They were now moving up the slope to the Tomb, through the long avenue of eternal trees. At its end, the avenue was blocked by Alvin's ship, looking strangely out of place in these familiar surroundings.

             "There," said Rorden suddenly, "is the greatest mystery of all. Who was the Master? Where did he get this ship and the three robots?"

             "I've been thinking about that," answered Theon. "We know that he came from the Seven Suns, and there might have been a fairly high culture there when civilization on Earth was at its lowest. The ship itself is obviously the work of the Empire.

             "I believe that the Master was escaping from his own people. Perhaps he had ideas with which they didn't agree: he was a philosopher, and a rather remarkable one. He found our ancestors friendly but superstitious and tried to educate them, but they misunderstood and distorted his teachings. The Great Ones were no more than the men of the Empire—only it wasn't Earth they had left, but the Universe itself. The Master's disciples didn't understand or didn't believe this, and all their mythology and ritual was founded on that false premise. One day I intend to go into the Master's history and find why he tried to conceal his past. I think it will be a very interesting story."

             "We've a good deal to thank him for," said Rorden as they entered the ship. "Without him we would never have learned the truth about the past."

             "I'm not so sure," said Alvin. "Sooner or later Vanamonde would have discovered us. And I believe there may be other ships hidden on Earth: one day I mean to find them."

             The city was now too distant to be recognized as the work of Man, and the curve of the planet was becoming visible. In a little while they could see the line of twilight, thousands of miles away on its never-ending march across the desert. Above and around were the stars, still brilliant for all the glory they had lost.

             For a long time Rorden stared at the desolate panorama he had never seen before. He felt a sudden contemptuous anger for the men of the past who had let Earth's beauty die through their own neglect. If one of Alvin's dreams came true, and the great transmutation plants still existed, it would not be many centuries before the oceans rolled again.

             There was so much to do in the years ahead. Rorden knew that he stood between two ages: around him he could feel the pulse of mankind beginning to quicken again. There were great problems to be faced, and Diaspar would face them. The recharting of the past would take centuries, but when it was finished Man would have recovered all that he had lost. And always now in the background would be the great enigma of Vanamonde—

             If Calitrax was right, Vanamonde had already evolved more swiftly than his creators had expected, and the philosophers of Lys had great hopes of future cooperation which they would confide to no one. They had become very attached to the childlike supermind, and perhaps they believed that they could foreshorten the eons which his natural evolution would require. But Rorden knew that the ultimate destiny of Vanamonde was something in which Man would play no part. He had dreamed, and he believed the dream was true, that at the end of the Universe Vanamonde and the Mad Mind must meet each other among the corpses of the stars.

             Alvin broke into his reverie and Rorden turned from the screen.

             "I wanted you to see this," said Alvin quietly. "It may be many centuries before you have another chance."

             "You're not leaving Earth?"

             "No: even if there are other civilizations in this Galaxy, I doubt if they'd be worth the trouble of finding. And there is so much to do here—"

             Alvin looked down at the great deserts, but his eyes saw instead the waters that would be sweeping over them a thousand years from now. Man had rediscovered his world, and he would make it beautiful while he remained upon it. And after that—

             "I am going to send this ship out of the Galaxy, to follow the Empire wherever it has gone. The search may take ages, but the robot will never tire. One day our cousins will receive my message, and they'll know that we are waiting for them here on Earth. They will return, and I hope that by then we'll be worthy of them, however great they have become."

             Alvin fell silent, staring into the future he had shaped but which he might never see. While Man was rebuilding his world, this ship would be crossing the darkness between the galaxies, and in thousands of years to come it would return. Perhaps he would be there to meet it, but if not, he was well content.

             They were now above the Pole, and the planet beneath them was an almost perfect hemisphere. Looking down upon the belt of twilight, Alvin realized that he was seeing at one instant both sunrise and sunset on opposite sides of the world. The symbolism was so perfect and so striking that he was to remember this moment all his life.