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 bow 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, be 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 bad not moved from its position. Perhaps it suspected nothing, and he had been quite wrong in ever imagining 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 bow 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,» be 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 pointthe 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 expain 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.
Seventeen
It was just as he had last seen it, the great ebon 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: