time present did not as much as disturb a molecule of air.
Twissell was hidden from Harlan's eyes by the bulk of the kettle, but then he rounded it, came into view. He was running.
A flick of his hand was enough to activate the mechanism that opened the door of the control room. He hurtled inside, shouting with an almost lyrical excitement. "It's done. It's done. We've closed the circle." He had breath to say no more.
Harlan made no answer.
Twissell stared out the window, his hands flat against the glass. Harlan noted the blotches of age upon them and the way in which they trembled. It was as though his mind no longer had the ability or the strength to filter the important from the inconsequential, but were selecting observational material in a purely random manner.
Wearily he thought: What does it matter? What does anything matter now?
Twissell said (Harlan heard him dimly), "I'll tell you now that I've been more anxious than I cared to admit. Sennor used to say once that this whole thing was impossible. He insisted something must happen to stop it-- What's the matter?"
He had turned at Harlan's odd grunt.
Harlan shook his head, managed a choked "Nothing."
Twissell left it at that and turned away. It was doubtful whether he spoke to Harlan or to the air. It was as though he were allowing years of pent-up anxieties to escape in words.
"Sennor," he said, "was the doubter. We reasoned with him and argued. We used mathematics and presented the results of generations of research that had preceded us in the physiotime of Eternity. He put it all to one side and presented his case by quoting the man-meetshimself paradox. You heard him talk about it. It's his favorite.
"We knew our own future, Sennor said. I, Twissell, knew, for instance, that I would survive, despite the fact that I would be quite old, until Cooper made his trip past the downwhen terminus. I knew other details of my future, the things I would do.
"Impossible, he would say. Reality must change to correct your knowledge, even if it meant the circle would never close and Eternity never established.
"Why he argued so, I don't know. Perhaps he honestly believed it, perhaps it was an intellectual game with him, perhaps it was just the desire to shock the rest of us with an unpopular viewpoint. In any case, the project proceeded and some of the memoir began to be fulfilled. We located Cooper, for instance, in the Century and Reality that the memoir gave us. Sennor's case was exploded by that alone, but it didn't bother him. By that time, he had grown interested in something else.
"And yet, and yet"-he laughed gently, with more than a trace of embarrassment, and let his cigarette, unnoticed, burn down nearly to his fingers-"you know I was never quite easy in my mind. Something might happen. The Reality in which Eternity was established might change in some way in order to prevent what Sennor called a paradox. It would have to change to one in which Eternity would not exist. Sometimes, in the dark of a sleeping period, when I couldn't sleep, I could almost persuade myself that that was indeed so. -and now it's all over and I laugh at myself as a senile fool."
Harlan said in a low voice, "Computer Sennor was right."
Twissell whirled. "What?"
"The project failed." Harlan's mind was coming out of the shadows (why, and into what, he was not sure). "The circle is not complete."
"What are you talking about?" Twissell's old hands fell on Harlan's shoulders with surprising strength. "You're ill, boy. The strain."
"Not ill. Sick of everything. You. Me. Not ill. The gauge. See for yourself."
"The gauge?" The hairline on the gauge stood at the 27th Century, hard against the right-hand extreme. "What happened?" The joy was gone from his face. Horror replaced it.
Harlan grew matter-of-fact. "I melted the locking mechanism, freed the thrust control."
"How could you--"
"I had a neuronic whip. I broke it open and used its micro-pile energy source in one flash, like a torch. There's what's left of it." He kicked at a small heap of metal fragments in one corner.
Twissell wasn't taking it in. "In the 27th? You mean Cooper's in the 27th--"
"I don't know where he is," said Harlan dully. "I shifted the thrust control downwhen, further down than the z4th. I don't know where. I didn't look. Then I brought it back. I still didn't look."
Twissell stared at him, his face a pale, unhealthy