Against the Fall of Night by Arthur C. Clarke

if he was following: her every movement told him: “Try and run away if you like—my mind is more powerful than yours.” And he knew that it was perfectly true.
    They were clear of the houses when he stopped and turned to his friend.
    “Good-bye, Theon,” he said, holding out his hands. “Thank you for all you’ve done. One day I’ll be back.”
    Seranis had stopped and was watching him intently. He smiled at her even while he measured the twenty feet of ground between them.
    “I know that you’re doing this against your will,” he said, “and I don’t blame you for it. I don’t like what I’m doing, either.” (That was not true, he thought. Already he was beginning to enjoy himself.) He glanced quickly around: no one was approaching and Seranis had not moved. She was still watching him, probably trying to probe into his mind. He talked quickly to prevent even the outlines of his plan from shaping among his thoughts.
    “I do not believe you are right,” he said, so unconscious of his intellectual arrogance that Seranis could not resist a smile. “It’s wrong for Lys and Diaspar to remain apart forever: one day they may need each other desperately. So I am going home with all that I have learned—and I do not think that you can stop me.”
    He waited no longer, and it was just as well. Seranis never moved, but instantly he felt his body slipping from his control. The power that had brushed aside his own will was even greater than he had expected, and he realized that many hidden minds must be aiding Seranis. Helplessly he began to walk back towards the center of the village, and for an awful moment he thought his plans had failed.
    Then there came a flash of steel and crystal, and the metal arms closed swiftly around him. His body fought against them, as he had known it must do, but his struggles were useless. The ground fell away beneath him and he caught a glimpse of Theon, frozen by surprise with a foolish smile upon his face.
    The robot was carrying him a dozen feet above the ground, much faster than a man could run. It took Seranis only a moment to understand his ruse, and his struggles died away as she relaxed her control. But she was not defeated yet, and presently there happened that which Alvin had feared and done his best to counteract.
    There were now two separate entities fighting inside his mind, and one of them was pleading with the robot, begging it to set him down again. The real Alvin waited, breathlessly, resisting only a little against forces he knew he could not hope to fight. He had gambled: there was no way of telling beforehand if the machine could understand orders as complex as those he had given it. Under no circumstances, he had told the robot, must it obey any further commands of his until he was safely inside Diaspar. Those were the orders. If they were obeyed, Alvin had placed his fate beyond the reach of human interferences.
    Never hesitating, the machine raced on along the path he had so carefully mapped out for it. A part of him was still pleading angrily to be released, but he knew now that he was safe. And presently Seranis understood that too, for the forces inside his brain ceased to war with one another. Once more he was at peace, as ages ago an earlier wanderer had been when, lashed to the mast of his ship, he had heard the song of the Sirens die away across the wine-dark sea.

Ten
Duplication
    “So you see,” concluded Alvin, “it will carry out any orders I give, no matter how complicated they are. But as soon as I ask questions about its origin, it simply freezes like that.”
    The machine was hanging motionless above the Master Associator, its crystal lenses glittering in the silver light like a cluster of jewels. Of all the robots which Rorden had ever met, this was by far the most baffling: he was now almost sure that it had been built by no human civilization. With such eternal servants it was not surprising that the Master’s personality had survived the