The City and the Stars / The Sands of Mars (24 page)

Here was the end of an evolution almost as long as Man’s. Its beginnings were lost in the mists of the Dawn Ages, when humanity had first learned the use of power and sent its noisy engines clanking about the world. Steam, water, wind— all had been harnessed for a little while and then abandoned. For centuries the energy of matter had run the world until it too had been superseded, and with each change the old machines were forgotten and new ones took their place. Very slowly, over thousands of years, the ideal of the perfect machine was approached— that ideal which had once been a dream, then a distant prospect, and at last reality:

No machine may contain any moving parts.

Here was the ultimate expression of that ideal. Its achievement had taken Man perhaps a hundred million years, and in the moment of his triumph he had turned his back upon the machine forever. It had reached finality, and thenceforth could sustain itself eternally while serving him.

Alvin no longer asked himself which of these silent white presences was the Central Computer. He knew that it comprised them all— and that it extended far beyond this chamber, including within its being all the countless other machines in Diaspar, whether they were mobile or motionless. As his own brain was the sum of many billion separate cells, arrayed throughout a volume of space a few inches across, so the physical elements of the Central Computer were scattered throughout the length and breadth of Diaspar. This chamber might hold no more than the switching system whereby all these dispersed units kept in touch with one another.

Uncertain where to go next, Alvin stared down the great sweeping ramps and across the silent arena. The Central Computer must know that he was here, as it knew everything that was happening in Diaspar. He could only wait for its instructions.

The now-familiar yet still awe-inspiring voice was so quiet and so close to him that he did not believe that his escort could also hear it. “Go down the left-hand ramp,” it said. “I will direct you from there.”

He walked slowly down the slope, the robot floating above him. Neither Jeserac nor the proctors followed; he wondered if they had received orders to remain here, or whether they had decided that they could supervise him just as well from their vantage point without the bother of making this long descent. Or perhaps they had come as close to the central shrine of Diaspar as they cared to approach.

At the foot of the ramp, the quiet voice redirected Alvin, and he walked between an avenue of sleeping titan shapes. Three times the voice spoke to him again, until presently he knew that he had reached his goal.

The machine before which he was standing was smaller than most of its companions, but he felt dwarfed as he stood beneath it. The five tiers with their sweeping horizontal lines gave the impression of some crouching beast, and looking from it to his own robot Alvin found it hard to believe that both were products of the same evolution, and both described by the same word.

About three feet from the ground a wide transparent panel ran the whole length of the structure. Alvin pressed his forehead against the smooth, curiously warm material and peered into the machine. At first he saw nothing; then, by shielding his eyes, he could distinguish thousands of faint points of light hanging in nothingness. They were ranged one beyond the other in a three-dimensional lattice, as strange and as meaningless to him as the stars must have been to ancient man. Though he watched for many minutes, forgetful of the passage of time, the colored lights never moved from their places and their brilliance never changed.

If he could look into his own brain, Alvin realized, it would mean as little to him. The machine seemed inert and motionless because he could not see its thoughts.

For the first time, he began to have some dim understanding of the powers and forces that sustained the city. All his life he had accepted without question the miracle of the synthesizers which age after age provided in an unending stream all the needs of Diaspar. Thousands of times he had watched that act of creation, seldom remembering that somewhere must exist the prototype of that which he had seen come into the world.

As a human mind may dwell for a little while upon a single thought, so the infinitely greater brains which were but a portion of the Central Computer could grasp and hold forever the most intricate ideas. The patterns of all created things were frozen in these eternal minds, needing only the touch of a human will to make them reality.

The world had indeed gone far since, hour upon hour, the first cavemen had patiently chipped their arrowheads and knives from the stubborn stone.

Alvin waited, not caring to speak until he had received some further sign of recognition. He wondered how the Central Computer was aware of his presence, and could see him and hear his voice. Nowhere were there any signs of sense organs— none of the grilles or screens or emotionless crystal eyes through which robots normally had knowledge of the world around them.

“State your problem,” said the quiet voice in his ear. It seemed strange that this overwhelming expanse of machinery should sum up its thoughts so softly. Then Alvin realized that he was flattering himself; perhaps not even a millionth part of the Central Computer’s brain was dealing with him. He was just one of the innumerable incidents that came to its simultaneous attention as it watched over Diaspar.

It was hard to talk to a presence who filled the whole of the space around you. Alvin’s words seemed to die in the empty air as soon as he had uttered them.

“What am I?” he asked.

If he had put the question to one of the information machines in the city, he knew what the reply would have been. Indeed, he had often done so, and they had always answered, “You are a Man.” But now he was dealing with an intelligence of an altogether different order, and there was no need for painstaking semantic accuracy. The Central Computer would know what he meant, but that did not mean that it would answer him.

Indeed, the reply was exactly what Alvin had feared.

“I cannot answer that question. To do so would be to reveal the purpose of my builders, and hence to nullify it.”

“Then my role was planned when the city was laid down?”

“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

I
t 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.