At the last moment, he drew his Robot back from the edge, stabbing half-blindly at the controls which propelled it. They had almost driven him to suicide. He must keep his mind a perfect blank--or, better still, think of something which would keep them at bay. Diane, his love for her--Diane.... A Robot waited for him at the top of the ramp. Those behind him were gaining rapidly, driving death-wishes deep within his brain. The Robot above him abruptly swung into motion, but Johnny desperately sidestepped the lunge which would have sent him hurtling to the floor of the rotunda. The other Robot checked its own inertia and came for Johnny again, huge arms swinging, trying to crush him within the metal chamber as Amos Westler had been crushed. Johnny parried the blows with his own metal arms, then reached out and heard machinery groan within his metal frame as he lifted the other Robot and hurled it in the path of his pursuers. There was a grinding, clattering crash of metal. Johnny saw three forms detach themselves from the arcing ramp and tumble, swinging and twisting in air grotesquely, to the floor, where they struck resoundingly and broke apart, the metal arms and legs flying. Then he was climbing again, the remaining Robots far below him and disorganized now. But soon, he knew, they would be capable of following. It was as Amos Westler had predicted. After a time, the ramp grew smaller. It no longer climbed now--it had soared high and now was just below the girdered ceiling. It was hardly wide enough for Johnny's Robot, it shook dangerously with the tread of metal feet. Here, Johnny knew, was the sanctuary. This was the Achilles Heel. This was the entrance, this ramp which no Robot could traverse. Here the way led to self-functioning, self-repairing machinery, to Central Intelligence. Here was man's final hope in the eyes of the original inventor. Here was the guarantee that the Robots, if they became some Frankenstein monster, could be met and conquered. For no Robot could guard the final portal to Central Intelligence. No Robot could even draw close enough to alter the thin ramp. Johnny smiled grimly as comprehension grew. If Robots could become neurotic, this was the place for it. They could have employed their human servants, the Shining Ones, to alter the place, but would have divulged their secret in the process. Still smiling, Johnny halted his Robot, opened the face plate clumsily from the inside, and climbed out. He sat on the ramp and flexed stiff arms and legs, then stood up and heard the Robots below him. He could see them now, no longer advancing, milling about in confusion. Their weight would destroy the ramp, and they knew it. They could never hope to reach him. It was all so incredibly simple. Was it? _One Robot had been above him._ Then they knew he was coming. What had they prepared for him beyond the point where the Robots could not climb? Shrugging, he advanced warily.