The City And The Stars - Arthur C. Clarke [78]
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 specialised 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 ensure 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 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 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 thousand million 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 minds of the two robots made their delicate contact again. And then, without any warning, he was in Shalmirane.
CHAPTER SEVENTEEN
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 organised, 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