They made their longest pause at a tiny village almost hidden in a sea of tall golden grass, which soared high above their heads and which undulated in the gentle wind as if it was endowed with life. As they moved through it, they were continually overtaken by rolling waves as the countless blades bowed in unison above them. At first it was faintly disturbing, for Alvin had a foolish fancy that the grass was bending down to look at him, but after a while he found the continual motion quite restful.

  Alvin soon discovered why they had made this stop. Among the little crowd that had already gathered before the car came gliding into the village was a shy, dark girl whom Hilvar introduced as Nyara. They were obviously very pleased to see one another again, and Alvin felt envious of their patent happiness at this brief reunion. Hilvar was clearly torn between his duties as a guide and his desire to have no other company but Nyara, and Alvin soon rescued him from his quandary by setting off on a tour of exploration by himself. There was not much to see in the little village, but he took his time.

  When they started on their way again, there were many questions he was anxious to ask Hilvar. He could not imagine what love must be like in a telepathic society, and after a discreet interval he broached the subject. Hilvar was willing enough to explain, even though Alvin suspected that he had made his friend interrupt a prolonged and tender mental leave-taking.

  In Lys, it seemed, all love began with mental contact, and it might be months or years before a couple actually met. In this way, Hilvar explained, there could be no false impressions, no deceptions on either side. Two people whose minds were open to one another could hide no secrets. If either attempted it, the other partner would know at once that something was being concealed.

  Only very mature and well-balanced minds could afford such honesty; only love based upon absolute unselfishness could survive it. Alvin could well understand that such a love would be deeper and richer than anything his people could know; it could be so perfect, in fact, that he found it hard to believe that it could ever occur at all.

  Yet Hilvar assured him that it did, and became starry-eyed and lost in his own reveries when Alvin pressed him to be more explicit. There were some things that could not be communicated; one either knew them or one did not. Alvin decided sadly that he could never attain the kind of mutual understanding which these fortunate people had made the very basis of their lives.

  When the ground-car emerged from the savanna, which ended abruptly as though a frontier had been drawn beyond which the grass was not permitted to grow, there was a range of low, heavily wooded hills ahead of them. This was an outpost, Hilvar explained, of the main rampart guarding Lys. The real mountains lay beyond, but to Alvin even these small hills were an impressive and awe-inspiring sight.

  The car came to a halt in a narrow, sheltered valley which was still flooded by the warmth and light of the descending sun. Hilvar looked at Alvin with a kind of wide-eyed candor which, one could have sworn, was totally innocent of any guile.

  “This is where we start to walk,” he said cheerfully, beginning to throw equipment out of the vehicle. “We can’t ride any farther.”

  Alvin looked at the hills surrounding them, then at the comfortable seat in which he had been riding.

  “Isn’t there a way around?” he asked, not very hopefully.

  “Of course,” replied Hilvar. “But we’re not going around. We’re going to the top, which is much more interesting. I’ll put the car on automatic so that it will be waiting for us when we get down the other side.”

  Determined not to give in without a struggle, Alvin made one last effort.

  “It will soon be dark,” he protested. “We’ll never be able to go all that way before sunset.”

  “Exactly,” said Hilvar, sorting packages and equipment with incredible speed. “We’ll spend the night on the summit, and finish the journey in the morning.”

  For once, Alvin knew when he was beaten.

  The gear that they were carrying looked very formidable, but though it was bulky it weighed practically nothing. It was all packed in gravity-polarizing containers that neutralized its weight, leaving only inertia to be contended with. As long as Alvin moved in a straight line, he was not conscious that he was carrying any load. Dealing with these containers required a little practice, for if he attempted to make a sudden change of direction his pack seemed to develop a stubborn personality and did its best to keep him on his original course, until he had overcome its momentum.

  When Hilvar had adjusted all the straps and satisfied himself that everything was in order, they began to walk slowly up the valley. Alvin looked back wistfully as the ground-car retraced its track and disappeared from sight; he wondered how many hours would elapse before he could again relax in its comfort.

  Nevertheless, it was very pleasant climbing upward with the mild sun beating on their backs, and seeing ever-new vistas unfold around them. There was a partly obliterated path which disappeared from time to time but which Hilvar seemed able to follow even when Alvin could see no trace of it. He asked Hilvar what had made the path, and was told that there were many small animals in these hills— some solitary, and some living in primitive communities which echoed many of the features of human civilization. A few had even discovered, or been taught, the use of tools and fire. It never occurred to Alvin that such creatures might be other than friendly; both he and Hilvar took this for granted, for it had been so many ages since anything on Earth had challenged the supremacy of Man.

  They had been climbing for half an hour when Alvin first noticed the faint, reverberating murmur in the air around him. He could not detect its source, for it seemed to come from no particular direction. It never ceased, and it grew steadily louder as the landscape widened around them. He would have asked Hilvar what it was, but it had become necessary to save his breath for more essential purposes.

  Alvin was in perfect health; indeed, he had never had an hour’s illness in his life. But physical well-being, however important and necessary it might be, was not sufficient for the task he was facing now. He had the body, but he did not possess the skill. Hilvar’s easy strides, the effortless surge of power which took him up every slope, filled Alvin with envy— and a determination not to give in while he could still place one foot in front of the other. He knew perfectly well that Hilvar was testing him, and did not resent the fact. It was a good-natured game, and he entered into the spirit of it even while the fatigue spread slowly through his legs.

  Hilvar took pity on him when they had completed two-thirds of the ascent, and they rested for a while propped up against a westward-facing bank, letting the mellow sunlight drench their bodies. The throbbing thunder was very strong now, and although Alvin questioned him Hilvar refused to explain it. It would, he said, spoil the surprise if Alvin knew what to expect at the end of the climb.

  They were now racing against the sun, but fortunately the final ascent was smooth and gentle. The trees that had covered the lower part of the hill had now thinned out, as if they too were tired of the fight against gravity, and for the last few hundred yards the ground was carpeted with short, wiry grass on which it was very pleasant to walk. As the summit came in sight, Hilvar put forth a sudden burst of energy and went racing up the slope. Alvin decided to ignore the challenge; indeed, he had no choice. He was quite content to plod steadily onward, and when he had caught up with Hilvar to collapse in contented exhaustion by his side.

  Not until he had regained his breath was he able to appreciate the view spread out beneath him, and to see the origin of the endless thunder which now filled the air. The ground ahead fell away steeply from the crest of the hill— so steeply, indeed, that it soon became an almost vertical cliff. And leaping far out from the face of the cliff was a mighty ribbon of water, which curved out through space to crash into the rocks a thousand feet below. There it was lost in a shimmering mist of spray, while up from the depths rose that ceaseless, drumming thunder that reverberated in hollow echoes from the hills on eith
er side.

  Most of the waterfall was now in shadow, but the sunlight streaming past the mountain still illuminated the land beneath, adding the final touch of magic to the scene. For quivering in evanescent beauty above the base of the fall was the last rainbow left on Earth.

  Hilvar waved his arm in a sweep which embraced the whole horizon.

  “From here,” he said, raising his voice so that it could be heard above the thunder of the waterfall, “you can see right across Lys.”

  Alvin could well believe him. To the north lay mile upon mile of forest, broken here and there by clearings and fields and the wandering threads of a hundred rivers. Hidden somewhere in that vast panorama was the village of Airlee, but it was hopeless to try to find it. Alvin fancied that he could catch a glimpse of the lake past which the path led to the entrance into Lys, but decided that his eyes had tricked him. Still farther north, trees and clearings alike were lost in a mottled carpet of green, rucked here and there by lines of hills. And beyond that, at the very edge of vision, the mountains that hemmed Lys from the desert lay like a bank of distant clouds.

  East and west the view was little different, but to the south the mountains seemed only a few miles away. Alvin could see them very clearly, and he realized that they were far higher than the little peak on which he was standing. They were separated from him by country that was much wilder than the land through which he had just passed. In some indefinable way it seemed deserted and empty, as if Man had not lived here for many, many years.

  Hilvar answered Alvin’s unspoken question.

  “Once that part of Lys was inhabited,” he said. “I don’t know why it was abandoned, and perhaps one day we shall move into it again. Only the animals live there now.”

  Indeed, there was nowhere any sign of human life— none of the clearings or well-disciplined rivers that spoke of Man’s presence. Only in one spot was there any indication that he had ever lived here, for many miles away a solitary white ruin jutted above the forest roof like a broken fang. Elsewhere, the jungle had returned to its own.

  The sun was sinking below the western walls of Lys. For a breathless moment, the distant mountains seemed to burn with golden flames; then the land they guarded was swiftly drowned with shadow and the night had come.

  “We should have done this before,” said Hilvar, practical as ever, as he started to unload their equipment. “It’ll be pitch dark in five minutes— and cold, too.”

  Curious pieces of apparatus began to cover the grass. A slim tripod extended a vertical rod carrying a pear-shaped bulge at its upper end. Hilvar raised this until the pear was just clear of their heads, and gave some mental signal which Alvin could not intercept. At once their little encampment was flooded with light, and the darkness retreated. The pear gave not only light but also heat, for Alvin could feel a gentle, caressing glow that seemed to sink into his very bones.

  Carrying the tripod in one hand and his pack in the other, Hilvar walked down the slope while Alvin hurried behind, doing his best to keep in the circle of light. He finally pitched camp in a small depression a few hundred yards below the crest of the hill, and started to put the rest of his equipment into operation.

  First came a large hemisphere of some rigid and almost invisible material which englobed them completely and protected them from the cool breeze which had now begun to blow up the face of the hill. The dome appeared to be generated by a small rectangular box which Hilvar placed on the ground and then ignored completely, even to the extent of burying it beneath the rest of his paraphernalia. Perhaps this also projected the comfortable, semitransparent couches on which Alvin was so glad to relax. It was the first time he had seen furniture materialized in Lys, where it seemed to him that the houses were terribly cluttered up with permanent artifacts which would be much better kept safely out of the way in Memory Banks.

  The meal which Hilvar produced from yet another of his receptacles was also the first purely synthetic one that Alvin had eaten since reaching Lys. There was a steady blast of air, sucked through some orifice in the dome overhead, as the matter-converter seized its raw material and performed its everyday miracle. On the whole, Alvin was much happier with purely synthetic food. The way in which the other kind was prepared struck him as being appallingly unhygienic, and at least with the matter-converters you knew exactly what you were eating.

  They settled down for their evening meal as the night deepened around them and the stars came out. When they had finished, it was completely dark beyond their circle of light, and at the edge of that circle Alvin could see dim shapes moving as the creatures of the forest crept out of their hiding places. From time to time he caught the glint of reflected light as pale eyes stared back at him, but whatever beasts were watching out there would come no closer, so he could see nothing more of them.

  It was very peaceful, and Alvin felt utterly content. For a while they lay on their couches and talked about the things that they had seen, the mystery that enmeshed them both, and the many ways in which their two cultures differed. Hilvar was fascinated by the miracle of the Eternity Circuits which had put Diaspar beyond the reach of time, and Alvin found some of his questions very hard to answer.

  “What I don’t understand,” said Hilvar, “is how the designers of Diaspar made certain that nothing would ever go wrong with the memory circuits. You tell me that the information defining the city, and all the people who live in it, is stored as patterns of electric charge inside crystals. Well, crystals will last forever— but what about all the circuits associated with them? Aren’t there ever any failures of any kind?”

  “I asked Khedron that same question, and he told me that the Memory Banks are virtually triplicated. Any one of the three banks can maintain the city, and if anything goes wrong with one of them, the other two automatically correct it. Only if the same failure occurred simultaneously in two of the banks would any permanent damage be done— and the chances of that are infinitesimal.”

  “And how is the relation maintained between the pattern stored in the memory units and the actual structure of the city? Between the plan, as it were, and the thing it describes?”

  Alvin was now completely out of his depth. He knew that the answer involved technologies that relied on the manipulation of space itself— but how one could lock an atom rigidly in the position defined by data stored elsewhere was something he could not begin to explain.

  On a sudden inspiration, he pointed to the invisible dome protecting them from the night.

  “Tell me how this roof above our heads is created by that box you’re sitting on,” he answered, “and then I’ll explain how the Eternity Circuits work.”

  Hilvar laughed.

  “I suppose it’s a fair comparison. You’d have to ask one of our field theory experts if you wanted to know that. I certainly couldn’t tell you.”

  The reply made Alvin very thoughtful. So there were still men in Lys who understood how their machines worked; that was more than could be said of Diaspar.

  Thus they talked and argued, until presently Hilvar said: “I’m tired. What about you— are you going to sleep?”

  Alvin rubbed his still-weary limbs.

  “I’d like to,” he confessed, “but I’m not sure I can. It still seems a strange custom to me.”

  “It is a good deal more than a custom,” smiled Hilvar. “I have been told that it was once a necessity to every human being. We still like to sleep at least once a day, even if only for a few hours. During that time the body refreshes itself, and the mind as well. Does no one in Diaspar ever sleep?”

  “Only on very rare occasions,” said Alvin. “Jeserac, my tutor, has done it once or twice, after he had made some exceptional mental effort. A well-designed body should have no need for such rest periods; we did away with them millions of years ago.”

  Even as he spoke these rather boastful words, his actions belied them. He felt a weariness such as he had never before known; it seemed to spread from his calves and thighs until it flowe
d through all his body. There was nothing unpleasant about the sensation— rather the reverse. Hilvar was watching him with an amused smile, and Alvin had enough faculties left to wonder if his companion was exercising any of his mental powers upon him. If so, he did not object in the least.

  The light flooding down from the metal pear overhead sank to a faint glow, but the warmth it was radiating continued unabated. By the last flicker of light, Alvin’s drowsy mind registered a curious fact which he would have to inquire about in the morning.

  Hilvar had stripped off his clothes, and for the first time Alvin saw how much the two branches of the human race had diverged. Some of the changes were merely ones of emphasis or proportion, but others, such as the external genitals and the presence of teeth, nails, and definite body hair, were more fundamental. What puzzled him most of all, however, was the curious small hollow in the pit of Hilvar’s stomach.

  When, some days later, he suddenly remembered the subject, it took a good deal of explaining. By the time that Hilvar had made the functions of the navel quite clear, he had uttered many thousands of words and drawn half a dozen diagrams.

  And both he and Alvin had made a great step forward in understanding the basis of each other’s cultures.