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 its 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.»
This 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 flowed 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.
Twelve
The night was at its deepest when Alvin woke. Something had disturbed him, some whisper of sound that had crept into his mind despite the endless thunder of the falls. He sat up in the darkness, straining his eyes across the hidden land, while with indrawn breath he listened to the drumming roar of the water and the softer, more fugitive sounds of the creatures of the night.