Anthony didn't think so. Weeks passed, then months. The robot had progressively done more and more, as the Mercury Computer had been placed, progressively, under a more and more complex programming. (William had a tendency to refer to the Mercury Computer as a brain, but Anthony wouldn't allow it.) And all that happened wasn't good enough.

"It's not good enough, William," he said finally. He had not slept the night before.

"Isn't that strange?" said William coolly. "I was going to say that I thought we had it about beaten."

Anthony held himself together with difficulty. The strain of working with William and of watching the robot fumble was more than he could bear. "I'm going to resign, William. The whole job. I'm sorry…It's not you."

"But it is I, Anthony."

"It isn't all you, William. It's failure. We won't make it. You see how clumsily the robot handles himself, even though he's on Earth, only a thousand miles away, with the signal round trip only a tiny fraction of a second in time. On Mercury, there will be minutes of delay, minutes for which the Mercury Computer will have to allow. It's madness to think it will work."

William said, "Don't resign, Anthony. You can't resign now. I suggest we have the robot sent to Mercury. I'm convinced he's ready."

Anthony laughed loudly and insultingly. "You're crazy, William."

"I'm not. You seem to think it will be harder on Mercury, but it won't be. It's harder on Earth. This robot is designed for one-third Earth-normal gravity, and he's working in Arizona at full gravity. He's designed for 400° C, and he's got 300° C. He's designed for vacuum and he's working in an atmospheric soup."

"That robot can take the difference."

"The metal structure can, I suppose, but what about the Computer right here? It doesn't work well with a robot that isn't in the environment he's designed for…Look, Anthony, if you want a computer that is as complex as a brain, you have to allow for idiosyncrasies…Come, let's make a deal. If you will push, with me, to have the robot sent to Mercury, that will take six months, and I will take a sabbatical for that period. You will be rid of me."

"Who'll take care of the Mercury Computer?"

"By now you understand how it works, and I'll have my two men here to help you."

Anthony shook his head defiantly. "I can't take the responsibility for the Computer, and I won't take the responsibility for suggesting that the robot be sent to Mercury. It won't work."

"I'm sure it will."

"You can't be sure. And the responsibility is mine. I'm the one who'll bear the blame. It will be nothing to you."

Anthony later remembered this as a crucial moment. William might have let it go. Anthony would have resigned. All would have been lost.

But William said, "Nothing to me? Look, Dad had this thing about Mom. All right. I'm sorry, too. I'm as sorry as anyone can be, but it's done, and there's something funny that has resulted. When I speak of Dad, I mean your Dad, too, and there's lots of pairs of people who can say that: two brothers, two sisters, a brother and sister. And then when I say Mom, I mean your Mom, and there are lots of pairs who can say that, too. But I don't know any other pair, nor have I heard of any other pair, who can share both Dad and Mom."

"I know that," said Anthony grimly. "Yes, but look at it from my standpoint," said William hurriedly. "I'm a homologist. I work with gene patterns. Have you ever thought of our gene patterns? We share both parents, which means that our gene patterns are closer together than any other pair on this planet. Our very faces show it."

"I know that, too."

"So that if this project were to work, and if you were to gain glory from it, it would be your gene pattern that would have been proven highly useful to mankind-and that would mean very much my gene pattern as well…Don't you see, Anthony? I share your parents, your face, your gene pattern, and therefore either your glory or your disgrace. It is mine almost as much as yours, and if any credit or blame adheres to me, it is yours almost as much as mine, too. I've got to be interested in your success. I've a motive for that which no one else on Earth has- a purely selfish one, one so selfish you can be sure it's there. I'm on your side, Anthony, because you're very nearly me!"

They looked at each other for a long time, and for the first time, Anthony did so without noticing the face he shared.

William said, "So let us ask that the robot be sent to Mercury."

And Anthony gave in. And after Dmitri had approved the request - he had been waiting to, after all- Anthony spent much of the day in deep thought.

Then he sought out William and said, "Listen!"

There was a long pause which William did not break. Anthony said again, "Listen!" William waited patiently.

Anthony said, "There's really no need for you to leave. I'm sure you wouldn't like to have the Mercury Computer tended by anyone but yourself."

William said, "You mean you intend to leave?" Anthony said, "No, I'll stay, too."

William said, "We needn't see much of each other."

All of this had been, for Anthony, like speaking with a pair of hands clenched about his windpipe. The pressure seemed to tighten now, but he managed the hardest statement of all.

"We don't have to avoid each other. We don't have to."

William smiled rather uncertainly. Anthony didn't smile at all; he left quickly.

William looked up from his book. It was at least a month since he had ceased being vaguely surprised at having Anthony enter.

He said, " Anything wrong?"

"Who can say? They're coming in for the soft landing. Is the Mercury Computer in action?"

William knew Anthony knew the Computer status perfectly, but he said, "By tomorrow morning, Anthony."

" And there are no problems?"

"None at all."

"Then we have to wait for the soft landing."

"Yes."

Anthony said, "Something will go wrong."

"Rocketry is surely an old hand at this. Nothing will go wrong."

"So much work wasted."

"It's not wasted yet. It won't be."

Anthony said, "Maybe you're right." Hands deep in his pockets, he drifted away, stopping at the door just before touching contact. "Thanks!"

"For what, Anthony?"

"For being- comforting."

William smiled wryly and was relieved his emotions didn't show.

Virtually the entire body of personnel of the Mercury Project was on hand for the crucial moment. Anthony, who had no tasks to perform, remained well to the rear, his eyes on the monitors. The robot had been activated and there were visual messages being returned.

At least they came out as the equivalent of visual-and they showed as yet nothing but a dim glow of light which was, presumably, Mercury's surface.

Shadows flitted across the screen, probably irregularities on that surface. Anthony couldn't tell by eye alone, but those at the controls, who were analyzing the data by methods more subtle than could be disposed of by unaided eye, seemed calm. None of the little red lights that might have betokened emergency were lighting. Anthony was watching the key observers rather than the screen.

He should be down with William and the others at the Computer. It was going to be thrown in only when the soft landing was made. He should be. He couldn't be.