The City and the Stars/The Sands of Mars

by Arthur C. Clarke

  “That can be said of all men.”

  This reply made Alvin pause. It was true enough; the human inhabitants of Diaspar had been designed as carefully as its machines. The fact that he was a Unique gave Alvin rarity, but there was no necessary virtue in that.

  He knew that he could learn nothing further here regarding the mystery of his origin. It was useless to try to trick this vast intelligence, or to hope that it would disclose information it had been ordered to conceal. Alvin was not unduly disappointed; he felt that he had already begun to glimpse the truth, and in any case this was not the main purpose of his visit.

  He looked at the robot he had brought from Lys, and wondered how to make his next step. It might react violently if it knew what he was planning, so it was essential that it should not overhear what he intended to say to the Central Computer.

  “Can you arrange a zone of silence?” he asked.

  Instantly, he sensed the unmistakable “dead” feeling, the total blanketing of all sounds, which descended when one was inside such a zone. The voice of the Computer, now curiously flat and sinister, spoke to him: “No one can hear us now. Say what you wish.”

  Alvin glanced at the robot; it had not moved from its position. Perhaps it suspected nothing, and he had been quite wrong in ever imaginating that it had plans of its own. It might have followed him into Diaspar like a faithful, trusting servant, in which case what he was planning now seemed a particularly churlish trick.

  “You have heard how I met this robot,” Alvin began. “It must possess priceless knowledge about the past, going back to the days before the city as we know it existed. It may even be able to tell us about the other worlds than Earth, since it followed the Master on his travels. Unfortunately, its speech circuits are blocked. I do not know how effective that block is, but I am asking you to clear it.”

  His voice sounded dead and hollow as the zone of silence absorbed every word before it could form an echo. He waited, within that invisible and unreverberant void, for his request to be obeyed or rejected.

  “Your order involves two problems,” replied the Computer. “One is moral, one technical. This robot was designed to obey the orders of a certain man. What right have I to override them, even if I can?”

  It was a question which Alvin had anticipated and for which he had prepared several answers.

  “We do not know what exact form the Master’s prohibition took,” he replied. “If you can talk to the robot, you may be able to persuade it that the circumstances in which the block was imposed have now changed.”

  It was, of course, the obvious approach. Alvin had attempted it himself, without success, but he hoped that the Central Computer, with its infinitely greater mental resources, might accomplish what he had failed to do.

  “That depends entirely upon the nature of the block,” came the reply. “It is possible to set up a block which, if tampered with, will cause the contents of the memory cells to be erased. However, I think it unlikely that the Master possessed sufficient skill to do that; it requires somewhat specialized techniques. I will ask your machine if an erasing circuit has been set up in its memory units.”

  “But suppose,” said Alvin in sudden alarm, “it causes erasure of memory merely to ask if an erasing circuit exists?”

  “There is a standard procedure for such cases, which I shall follow. I shall set up secondary instructions, telling the machine to ignore my question if such a situation exists. It is then simple to insure that it will become involved in a logical paradox, so that whether it answers me or whether it says nothing it will be forced to disobey its instructions. In such an event all robots act in the same manner, for their own protection. They clear their input circuits and act as if no question has been asked.”

  Alvin felt rather sorry that he had raised the point, and after a moment’s mental struggle decided that he too would adopt the same tactics and pretend that he had never been asked the question. At least he was reassured on one point— the Central Computer was fully prepared to deal with any booby traps that might exist in the robot’s memory units. Alvin had no wish to see the machine reduced to a pile of junk; rather than that, he would willingly return it to Shalmirane with its secrets still intact.

  He waited with what patience he could while the silent, impalpable meeting of two intellects took place. Here was an encounter between two minds, both of them created by human genius in the long-lost golden age of its greatest achievement. And now both were beyond the full understanding of any living man.

  Many minutes later, the hollow, anechoic voice of the Central Computer spoke again.

  “I have established partial contact,” it said. “At least I know the nature of the block, and I think I know why it was imposed. There is only one way in which it can be broken. Not until the Great Ones come to Earth will this robot speak again.”

  “But that is nonsense!” protested Alvin. “The Master’s other disciple believed in them, too, and tried to explain what they were like to us. Most of the time it was talking gibberish. The Great Ones never existed, and never will exist.”

  It seemed a complete impasse, and Alvin felt a sense of bitter, helpless disappointment. He was barred from the truth by the wishes of a man who had been insane, and who had died a billion years ago.

  “You may be correct,” said the Central Computer, “in saying that the Great Ones never existed. But that does not mean that they never will exist.”

  There was another long silence while Alvin considered the meaning of this remark, and while the mind of the two robots made their delicate contact again. And then, without any warning, he was in Shalmirane.

  CHAPTER

  17

  It was just as he had last seen it, the great ebony bowl drinking the sunlight and reflecting none back to the eye. He stood among the ruins of the fortress, looking out across the lake, whose motionless waters showed that the giant polyp was now a dispersed cloud of animalcules and no longer an organized, sentient being.

  The robot was still beside him, but of Hilvar there was no sign. He had no time to wonder what that meant, or to worry about his friend’s absence, for almost at once there occurred something so fantastic that all other thoughts were banished from his mind.

  The sky began to crack in two. A thin wedge of darkness reached from horizon to zenith, and slowly widened as if night and chaos were breaking in upon the Universe. Inexorably the wedge expanded until it embraced a quarter of the sky. For all his knowledge of the real facts of astronomy, Alvin could not fight against the overwhelming impression that he and his world lay beneath a great blue dome— and that something was now breaking through that dome from outside.

  The wedge of night had ceased to grow. The powers that had made it were peering down into the toy universe they had discovered, perhaps conferring among themselves as to whether it was worth their attention. Underneath that cosmic scrutiny, Alvin felt no alarm, no terror. He knew that he was face to face with power and wisdom, before which a man might feel awe but never fear.

  And now they had decided— they would waste some fragments of Eternity upon Earth and its peoples. They were coming through the window they had broken in the sky.

  Like sparks from some celestial forge, they drifted down to Earth. Thicker and thicker they came, until a waterfall of fire was streaming down from heaven and splashing in pools of liquid light as it reached the ground. Alvin did not need the words that sounded in his ears like a benediction:

  “The Great Ones have come.”

  The fire reached him, and it did not burn. It was everywhere, filling the great bowl of Shalmirane with its golden glow. As he watched in wonder, Alvin saw that it was not a featureless flood of light, but that it had form and structure. It began to resolve itself into distinct shapes, to gather into separate fiery whirlpools. The whirlpools spun more and more swiftly on their axes, their centers rising to form columns within which Alvin could glimpse mysterious evanescent shapes. From these glowing totem poles came a faint mus
ical note, infinitely distant and hauntingly sweet.

  “The Great Ones have come.”

  This time there was a reply. As Alvin heard the words: “The servants of the Master greet you. We have been waiting for your coming,” he knew that the barriers were down. And in that moment, Shalmirane and its strange visitors were gone, and he was standing once more before the Central Computer in the depths of Diaspar.

  It had all been illusion, no more real than the fantasy world of the sagas in which he had spent so many of the hours of his youth. But how had it been created; whence had come the strange images he had seen?

  “It was an unusual problem,” said the quiet voice of the Central Computer. “I knew that the robot must have some visual conception of the Great Ones in its mind. If I could convince it that the sense impressions it received coincided with that image, the rest would be simple.”

  “And how did you do that?”

  “Basically, by asking the robot what the Great Ones were like, and then seizing the pattern it formed in its thoughts. The pattern was very incomplete, and I had to improvise a good deal. Once or twice the picture I created began to depart badly from the robot’s conception, but when that happened I could sense the machine’s growing perplexity and modify the image before it became suspicious. You will appreciate that I could employ hundreds of circuits where it could employ only one, and switch from one image to the other so quickly that the change could not be perceived. It was a kind of conjuring trick; I was able to saturate the robot’s sensory circuits and also to overwhelm its critical faculties. What you saw was only the final, corrected image— the one which best fitted the Master’s revelation. It was crude, but it sufficed. The robot was convinced of its genuineness long enough for the block to be lifted, and in that moment I was able to make complete contact with its mind. It is no longer insane; it will answer any questions you wish.”

  Alvin was still in a daze; the afterglow of that spurious apocalypse still burned in his mind, and he did not pretend fully to understand the Central Computer’s explanation. No matter; a miracle of therapy had been accomplished, and the doors of knowledge had been flung open for him to enter.

  Then he remembered the warning that the Central Computer had given him, and asked anxiously: “What about the moral objections you had to overriding the Master’s orders?”

  “I have discovered why they were imposed. When you examine his life story in detail, as you can now do, you will see that he claimed to have produced many miracles. His disciples believed him, and their conviction added to his power. But, of course, all those miracles had some simple explanation— when indeed they occurred at all. I find it surprising that otherwise intelligent men should have let themselves be deceived in such a manner.”

  “So the Master was a fraud?”

  “No; it is not as simple as that. If he had been a mere impostor, he would never have achieved such success, and his movement would not have lasted so long. He was a good man, and much of what he taught was true and wise. In the end, he believed in his own miracles, but he knew that there was one witness who could refute them. The robot knew all his secrets; it was his mouthpiece and his colleague, yet if it were ever questioned too closely it could destroy the foundations of his power. So he ordered it never to reveal its memories until the last day of the Universe, when the Great Ones would come. It is hard to believe that such a mixture of deception and sincerity could exist in the same man, but such was the case.”

  Alvin wondered what the robot felt about this escape from its ancient bondage. It was, surely, a sufficiently complex machine to understand such emotions as resentment. It might be angry with the Master for having enslaved it— and equally angry with Alvin and the Central Computer for having tricked it back into sanity.

  The zone of silence had been lifted; there was no further need for secrecy. The moment for which Alvin had been waiting had come at last. He turned to the robot, and asked it the question that had haunted him ever since he had heard the story of the Master’s saga.

  And the robot replied.

  Jeserac and the proctors were still waiting patiently when he rejoined them. At the top of the ramp, before they entered the corridor, Alvin looked back across the cave, and the illusion was stronger than ever. Lying beneath him was a dead city of strange white buildings, a city bleached by a fierce light not meant for human eyes. Dead it might be, for it had never lived, but it pulsed with energies more potent than any that had ever quickened organic matter. While the world endured, these silent machines would still be here, never turning their minds from the thoughts that men of genius had given them long ago.

  Though Jeserac tried to question Alvin on the way back to the Council Chamber, he learned nothing of his talk with the Central Computer. This was not merely discretion on Alvin’s part; he was still too much lost in the wonder of what he had seen, too intoxicated with success, for any coherent conversation. Jeserac had to muster what patience he could, and hope that presently Alvin would emerge from his trance.

  The streets of Diaspar were bathed with a light that seemed pale and wan after the glare of the machine city. But Alvin scarcely saw them; he had no regard for the familiar beauty of the great towers drifting past him, or the curious glances of his fellow citizens. It was strange, he thought, how everything that had happened to him led up to this moment. Since he had met Khedron, events seemed to have moved automatically toward a predetermined goal. The monitors— Lys— Shalmirane— at every stage he might have turned aside with unseeing eyes, but something had led him on. Was he the maker of his own destiny, or was he especially favored by Fate? Perhaps it was merely a matter of probabilities, of the operation of the laws of chance. Any man might have found the path his footsteps had traced, and countless times in the past ages others must have gone almost as far. Those earlier Uniques, for example— what had happened to them? Perhaps he was merely the first to be lucky.

  All the way back through the streets, Alvin was establishing closer and closer rapport with the machine he had released from its age-long thralldom. It had always been able to receive his thoughts, but previously he had never known whether it would obey any orders he gave it. Now that uncertainty was gone; he could talk to it as he would to another human being, though since he was not alone he directed it not to use verbal speech but such simple thought images as he could understand. He sometimes resented the fact that robots could talk freely to one another on the telepathic level, whereas Man could not— except in Lys. Here was another power that Diaspar had lost or deliberately set aside.

  He continued the silent but somewhat one-sided conversation while they were waiting in the anteroom of the Council Chamber. It was impossible not to compare his present situation with that in Lys, when Seranis and her colleagues had tried to bend him to their wills. He hoped that there would be no need for another conflict, but if one should arise he was now far better prepared for it.

  His first glance at the faces of the Council members told Alvin what their decision had been. He was neither surprised nor particularly disappointed, and he showed none of the emotion the Councilors might have expected as he listened to the President’s summing-up.

  “Alvin,” began the President, “we have considered with great care the situation which your discovery has brought about, and we have reached this unanimous decision. Because no one wishes any change in our way of life, and because only once in many millions of years is anyone born who is capable of leaving Diaspar even if the means exists, the tunnel system to Lys is unnecessary and may well be a danger. The entrance to the chamber of the moving ways has therefore been sealed.

  “Moreover, since it is possible that there may be other ways of leaving the city, a search will be made of the monitor memory units. That search has already begun.

  “We have also considered what action, if any, need be taken with regard to you. In view of your youth, and the peculiar circumstances of your origin, it is felt that you cannot be censured for what you have done. Inde
ed, by disclosing a potential danger to our way of life, you have done the city a service, and we record our appreciation of that fact.”

  There was a murmur of applause, and expressions of satisfaction spread across the faces of the Councilors. A difficult situation had been speedily dealt with, they had avoided the necessity of reprimanding Alvin, and now they could go their ways again feeling that they, the chief citizens of Diaspar, had done their duty. With reasonably good fortune, it might be centuries before the need arose again.

  The President looked expectantly at Alvin; perhaps he hoped that Alvin would reciprocate and express his appreciation of the Council for letting him off so lightly. He was disappointed.

  “May I ask one question?” said Alvin politely.

  “Of course.”

  “The Central Computer, I take it, approved of your action?”

  In the ordinary way, this would have been an impertinent question to ask. The Council was not supposed to justify its decisions or explain how it had arrived at them. But Alvin himself had been taken into the confidence of the Central Computer, for some strange reason of its own. He was in a privileged position.

  The question clearly caused some embarrassment, and the reply came rather reluctantly.

  “Naturally we consulted with the Central Computer. It told us to use our own judgment.”

  Alvin had expected as much. The Central Computer would have been conferring with the Council at the same moment as it was talking to him— at the same moment, in fact, as it was attending to a million other tasks in Diaspar. It knew, as did Alvin, that any decision the Council now made was of no importance. The future had passed utterly beyond its control at the very moment when, in happy ignorance, it had decided that the crisis had been safely dealt with.

  Alvin felt no sense of superiority, none of the sweet anticipation of impending triumph, as he looked at these foolish old men who thought themselves the rulers of Diaspar. He had seen the real ruler of the city, and had spoken to it in the grave silence of its brilliant, buried world. That was an encounter which had burned most of the arrogance out of his soul, but enough was left for a final venture that would surpass all that had gone before.