Libby explained the dilemma as well as he could. Nancy wrinkled her nose. "That's a pretty prospect, I must say! Well, I guess that means back to the grind for little Nancy."

"What do you mean?"

"Have you ever taken care of a somnolent? No, of course you haven't. It gets tiresome. Turn them over, bend their arms, twiddle their tootsies, move their heads, close the tank and move on to the next one. I get so sick of human bodies that I'm tempted to take a vow of chastity."

"Don't commit yourself too far," advised Lazarus. "Why would you care, you old false alarm?"

Eleanor Johnson spoke up. "Fm glad to be in the ship again. Those slimy Jockaira-ugh!"

Nancy shrugged. "You're prejudiced, Eleanor. The Jocks are okay, in their way. Sure, they aren't exactly like us, but neither are dogs. You don't dislike dogs, do you?'

"That's what they are," Lazarus said soberly. "Dogs."

"Huh?"

"I don't mean that they are anything like dogs in most ways-they aren't even vaguely canine and they certainly are our equals and possibly our superiors in some things... but they are dogs just the same. Those things they call their 'gods' are simply their masters, their owners. We couldn't be domesticated, so the owners chucked us out."

Libby was thinking of the inexplicable telekinesis the Jockaira-or their masters-had used. "I wonder what it would have been like," he said thoughtfully, "if they had been able to domesticate us. They could have taught us a lot of wonderful things"

"Forget it," Lazarus said sharply. "It's not a man's place to be property."

"What is a man's place?"

"It's a man's business to be what he is... and be it in style!" Lazarus got up. "Got to go."

Libby started to leave also, but Nancy stopped him. "Don't go. I want to ask you some questions. What year is it back on~ Earth?"

Libby started to answer, closed his mouth. He started to answer a second time, finally said, "I don't know how to answer that question. It's like saying, 'How high is up?"

"I know I probably phrased it wrong," admitted Nancy. '1 didn't do very well in basic physics, but I did gather the idea that time is relative and simultaneity is an idea which applies only to two points close together in the same framework. But just the same, I want to know something. We've traveled a lot faster and farther than anyone ever did before, haven't we? Don't our clocks slow down, or something?"

Libby got that completely baffled look which mathematical-physicists wear whenever laymen try to talk about physics in nonmathematical language. "You're referring to the Lorentz-2 FitzGerald contraction. But, if you'll pardon me, anything one says about it in words is necessarily nonsense."

"Why?" she insisted.

"Because... well, because the language is inappropriate. The formulae used to describe the effect loosely called a contraction presuppose that the observer is part of the phenomenon. But verbal language contains the implicit assumption that we can stand outside the whole business and watch what goes on. The mathematical language denies the very possibility of any such outside viewpoint. Every observer has his own world line; he can't get outside it for a detached viewpoint."

"But suppose he did? Suppose we could see Earth right now?"

'~There I go again," Libby said miserably. "I tried to talk about it in words and all I did was to add to the confusion. There is no way to measure time in any absolute sense when two events are separated in a continuum. All you can measure is interval."

"Well, what is interval? So much space and so much time."

"No, no, no! It isn't that at all. Interval is... well, it's interval. I can write down formulae about it and show you how we use it, but it can't be defined in words. Look, Nancy, can you write the score for a full orchestration of a symphony in words?" -

"No. Well, maybe you could but it wonld take thousands of times as long."

"And musicians still could not play it until you put it back into musical notation. That's what I meant," Libby went on, "when I said that the language was inappropriate. I got into a difficulty like this once before in trying to describe the lightpressure drive. I was asked why, since the drive depends on loss of inertia, we people inside the ship had felt no loss of inertia. There was no answer, in words. Inertia isn't a word; it is a mathematical concept used in mathematically certain aspects of a plenum. I was stuck."

Nancy looked baffled but persisted doggedly. "My question still means something, even if I didn't phrase it right. You can't just tell me to run along and play. Suppose we turned around and went back the way we came, all the way to Earth, exactly the same trip but in reverse-just double the ship's time it has been so far. All right, what year would it be on Earth when we got there?'

"It would be... let me see, now-" The almost automatic processes of Libby's brain started running off the unbelievably huge and complex problem in accelerations, intervals, difform motion. He was approaching the answer in a warm glow of mathematical revery when the problem suddenly fell to pieces on him, became indeterminate. He abruptly realized that the problem had an unlimited number of equally valid answers.

But that was impossible. In the real world, not the fantasy world of mathematics, such a situation was absurd. Nancy's question had to have just one answer, unique and real.

Could the whole beautiful structure of relativity be an absurdity? Or did it mean that it was physically impossible ever to backtrack an interstellar distance?

"I'll have to give some thought to that one," Libby said hastily and left before Nancy could object.

But solitude and contemplation gave him no clue to the problem. It was not a failure of his mathematical ability; he was capable, he knew, of devising a mathematical description of any group of facts, whatever they might be. His difficulty lay in having too few facts. Until some observer traversed interstellar distances at speeds approximating the speed of light and returned to the planet from which he had started there could be no answer. Mathematics alone has no content, gives no answers.

Libby found himself wondering if the hills of his native Ozarks were still green, if the smell of wood smoke still clung to the trees in the autumn, then he recalled that the question lacked any meaning by any rules he knew of. He surrendered to an attack of homesickness such as he had not experienced since he was a youth in the Cosmic Construction Corps, making his first deep-space jump.

This feeling of doubt and uncertainty, the feeling of lostness and nostalgia, spread throughout the ship. On the first leg of their journey the Families had had the incentive that had kept the covered wagons crawling across the plains. But now they were going nowhere, one day led only to the next. Their long lives were become a meaningless burden.

Ira Howard, whose fortune established the Howard Foundation, was born in 1825 and died in 1873-of old age. He sold groceries to the Forty-niners in San Francisco, became a wholesale sutler in the American War of the Secession, multiplied his fortune during the tragic Reconstruction.

Howard was deathly afraid of dying. He hired the best doctors of his time to prolong his life. Nevertheless old age plucked him when most men are still young. But his will commanded that his money be used to lengthen human life. The administrators of the trust found no way to carry out his wishes other than by seeking out persons whose family trees showed congenital predispositions toward long life and then inducing them to reproduce in kind. Their method anticipated the work of Burbank; they may or may not have known of the illuminating researches of the Monk Gregor Mendel.

Mary Sperling put down the book she had been reading when Lazarus entered her stateeoom. He picked it up. "What are you reading, Sis? 'Ecclesiastes.' Hmm... I didn't know you were religious." He read aloud: