"Yes, indeed?"

"How fragile is the situation? Suppose something unexpected were to happen and I were to miss a day when I ought to have been teaching Cooper something vital."

"I don't understand you."

(Was it Harlan's imagination, or had a spark of alarm sprung to life in those old, tired eyes?)

"I mean, can the circle break? Let me put it this way. If an unexpected blow on the head puts me out of action at a time when the memoir distinctly states I am well and active, is the whole scheme disrupted? Or suppose, for some reason, I deliberately choose not to follow the memoir. What then?"

"But what puts all this in your mind?"

"It seems a logical thought. It seems to me that by a careless or willful action, I could break the circle, and well, what? Destroy Eternity? It seems so. If it is so," Harlan added composedly, "I ought to be told so that I may be careful to do nothing unfitting. Though I imagine it would take a rather unusual circumstance to drive me to such a thing."

Twissell laughed, but the laughter rang false and empty in Harlan's ear. "This is all purely academic, my boy. Nothing of this will happen since it hasn't happened. The full circle will not break."

"It might," said Harlan. "The girl of the 482nd--"

"Is safe," said Twissell. He rose impatiently. "There's no end to this kind of talk and I have quite enough of logic-chopping from the rest of the subcommittee in charge of the project. Meanwhile, I have yet to tell you what I originally called you here to hear and physiotime is still passing. Will you come with me?

Harlan was satisfied. The situation was clear and his power unmistakable. Twissell knew that Harlan could say, at will: "I will no longer have anything to do with Cooper." Twissell knew Harlan could at any moment destroy Eternity by giving Cooper significant information concerning the memoir.

Harlan had known enough to do this yesterday. Twissell had thought to overwhelm him with the knowledge of the importance of his task, but if the Computer had thought to force Harlan into line in that way, he was mistaken.

Harlan had made his threat very clear with respect to Noys's safety, and Twissell's expression as he had barked, "Is safe," showed he realized the nature of the threat.

Harlan rose and followed Twissell.

Harlan had never been in the room they now entered. It was large and looked as though walls had been knocked down for its sake. It had been entered through a narrow corridor which had been blocked off by a force-screen that did not go down until after a pause sufficient for Twissell's face to be scanned thoroughly by automatic machinery.

The largest part of the room was filled by a sphere that reached nearly to the ceiling. A door was open, showing four small steps leading to a well-lit platform within.

Voices sounded from inside and even as Harlan watched, legs appeared in the opening and descended the steps. A man emerged and another pair of legs appeared behind him. It was Sennor of the Allwhen Council and behind him was another of the group at the breakfast table.

Twissell did not look pleased at this. His voice, however, was restrained. "Is the subcommittee still here?"

"Only we two," said Sennor casually, "Rice and myself. A beautiful instrument we have here. It has the level of complexity of a spaceship."

Rice was a paunchy man with the perplexed look of one who is accustomed to being right yet finds himself unaccountably on the losing side of an argument. He rubbed his bulbous nose and said, "Sennor's mind is running on space-travel lately."

Sennor's bald head glistened in the light. "It's a neat point, Twissell," he said. "I put it to you. Is space-travel a positive factor or a negative factor in the calculus of Reality?"

"The question is meaningless," said Twissell impatiently. "What type of space-travel in what society under what circumstances?"

"Oh, come. Surely there's something to be said concerning spacetravel in the abstract."

"Only that it is self-limiting, that it exhausts itself and dies out."

"Then it is useless," said Sennor with satisfaction, "and therefore it is a negative factor. My view entirely."

"If you please," said Twissell, "Cooper will be here soon. We will need the floor clear."

"By all means." Sennor hooked an arm under that of Rice and led him away. His voice declaimed clearly as they departed. "Periodically, my dear Rice, all the mental effort of mankind is concentrated on space-travel, which is doomed to a frustrated end by the nature of things. I would set up the matrices except that I am certain this is obvious to you. With minds concentrated on space, there is neglect of the proper development of things earthly. I am preparing a thesis now for submission to the Council recommending that Realities be changed to eliminate all space-travel eras as a matter of course."

Rice's treble sounded. "But you can't be that drastic. Space-travel is a valuable safety-valve in some civilizations. Take Reality 54 of the 290th, which I happen to recall offhand. Now there--"

The voices cut off and Twissell said, "A strange man, Sennor. Intellectually, he's worth two of any of the rest of us, but his worth is lost in leapfrog enthusiasms."

Harlan said, "Do you suppose he can be right? About space-travel, I mean."

"I doubt it. We'd have a better chance of judging if Sennor would actually submit the thesis he mentioned. But he won't. He'll have a new enthusiasm before he's finished and drop the old. But never mind--" He brought the flat of his hand against the sphere so that it rang resoundingly, then brought his hand back so that he could remove a cigarette from his lip. He said, "Can you guess what this is, Technician?"

"Harlan said, "It looks like an outsize kettle with a top."

"Exactly. You're right. You've got it. Come on inside."

Harlan followed Twissell into the sphere. It was large enough to hold four or five men, but the interior was absolutely featureless. The floor was smooth, the curved wall was broken by two windows. That was all.

"No controls?" asked Harlan.

"Remote controls," said Twissell. He ran his hand over the smoothness of the wall and said, "Double walls. The entire interwall volume is given over to a self-contained Temporal Field. This instrument is a kettle that is not restricted to the kettle shafts but can pass beyond the downwhen terminus of Eternity. Its design and construction were made possible by valuable hints in the Mallansohn memoir. Come with me."

The control room was a cut-off corner of the large room. Harlan stepped in and stared somberly at immense bus bars.

Twissell said, "Can you hear me, boy?"

Harlan started and looked about. He had not been aware that Twissell had not followed him inside. He stepped automatically to the window and Twissell waved to him. Harlan said, "I can hear you, sir. Do you want me outside?"

"Not at all. You are locked in."

Harlan sprang to the door and his stomach turned into a series of cold, wet knots. Twissell was correct and what in Time was going on?

Twissell said, "You will be relieved to know, boy, that your responsibility is over. You were worried about that responsibility; you asked searching questions about it; and I think I know what you meant. This should not be your responsibility. It is mine alone. Unfortunately, we must have you in the control room, since it is stated that you were there and handled the controls. It is stated in the Mallansohn memoir. Cooper will see you through the window and that will take care of that.

"Furthermore, I will ask you to make the final contact according to instructions I will give you. If you feel that that, too, is too great a responsibility, you may relax. Another contact in parallel with yours is in charge of another man. If, for any reason, you are unable to operate the contact, he will do so. Furthermore, I will cut off radio transmission from within the control room. You will be able to hear us but not to speak to us. You need not fear, therefore, that some involuntary exclamation from you will break the circle."