'Because I know that he was planning an experiment which would entail the breaking of security regulations. Events since, as nearly as I can make them out, flow naturally from the supposition that security regulations have indeed been broken. I can presume, then, that the experiment has at least been attempted. I must discover whether it has been successfully concluded.'

'Professor Boulder,' said the Boss, 'I believe you can read Greek.'

'Yes, I can,' - coolly.

'And have translated chemical texts for Professor Tywood on government money.'

'Yes - as a legally employed consultant'

'Yet such translation, under the circumstances, constitutes a crime, since it makes you an accessory to Tywood's crime.'

'You can establish a connection?'

'Can't you? Or haven't you heard of Tywood's notion on time travel, or... what do you call it... micro-temporal-trahslation?'

'Ah?' and Boulder smiled a little. 'He's told you, then.'

'No, he hasn't,' said the Boss, harshly. 'Professor Tywood is dead.'

'What?' Then - 'I don't believe you.'

'He died of apoplexy. Look at this.'

He had one of the photographs taken that first night in his wall safe. Tywood's face was distorted but recognizable -sprawled and dead.

Boulder 's breath went in and out as if the gears were clogged. He stared at the picture for three full minutes by the electric clock on the wall. 'Where is this place?' he asked.

'The Atomic Power Plant.'

'Had he finished his experiment?'

The Boss shrugged: There's no way of telling. He was dead when we found him.'

Boulder 's lips were pinched and colorless. 'That must be determined, somehow. A commission of scientists must be established, and, if necessary, the experiment must be repeated -'

But the Boss just looked at him, and reached for a cigar. I've never seen him take longer - and when he put it down, curled in its unused smoke, he said: 'Tywood wrote an article for a magazine, twenty years ago -'

'Oh,' and the professor's lips twisted, 'is that what gave you your clue? You may ignore that. The man is only a physical scientist and knows nothing of either history or sociology. A schoolboy's dreams and nothing more.'

'Then, you don't think sending your translation back will inaugurate a Golden Age, do you?'

'Of course not. Do you think you can graft the developments of two thousand years of slow labor onto a child society not ready for it? Do you think a great invention or a great scientific principle is born full-grown in the mind of a genius divorced from his cultural milieul Newton's enunciation of the Law of Gravity was delayed for twenty years because the then-current figure for the Earth's diameter was wrong by ten percent. Archimedes almost discovered calculus, but failed because Arabic numerals, invented by some nameless Hindu or group of Hindus, was unknown to him.

'For that matter, the mere existence of a slave society in ancient Greece and Rome meant that machines could scarcely attract much attention - slaves being so much cheaper and more adaptable. And men of true intellect could scarcely be expected to spend their energies on devices intended for manual labor. Even Archimedes, the greatest engineer of antiquity, refused to publish any of his practical inventions - only mathematic abstractions. And when a young man asked Plato of what use geometry was, he was forthwith expelled from the Academy as a man with a mean, unphilosophic soul.

'Science does not plunge forward - it inches along in the directions permitted by the greater forces that mold society and which are in turn molded by society. And no great man advances but on the shoulders of the society that surrounds him-'

The Boss interrupted him at that point. 'Suppose you tell us what your part in Tywood's work was, then. We'll take your word for it that history cannot be changed.'

'Oh it can, but not purposefully - You see, when Tywood first requested my services in the matter of translating certain textbook passages into Greek, I agreed for the money involved. But he wanted the translation on parchment; he insisted on the use of ancient Greek terminology - the language of Plato, to use his words - regardless of how I had to twist the literal significance of passages, and he wanted it hand-written in rolls.

'I was curious. I, too, found his magazine article. It was difficult for me to jump to the obvious conclusion, since the achievements of modern science transcend the imaginings of philosophy in so many ways. But I learned the truth eventually, and it was at once obvious that Tywood's theory of changing history was infantile. There are twenty million variables for every instant of time, and no system of mathematics - no mathematic psychohistory, to coin a phrase - has yet been developed to handle that ocean of varying functions.

'In short, any variation of events two thousand years ago would change all subsequent history, but in no predictable way.'

The boss suggested, with a false quietness: 'Like the pebble that starts the avalanche, right?'

'Exactly. You have some understanding of the situation, I see. I thought deeply for weeks before I proceeded, and then I realized how I must act - must act.'

There was a low roar. The Boss stood up and his chair went over backward. He swung around his desk, and he had a hand on Boulder 's throat. I was stepping out to stop him, but he waved me back -

He was only tightening the necktie a.little. Boulder could still breathe. He had gone very white, and for all the time that the Boss talked, he restricted himself to just that - breathing.

And the Boss said: 'Sure, I can see how you decided you must act. I know that some of you brain-sick philosophers think the world needs fixing. You want to throw the dice again and see what turns up. Maybe you don't even care if you're alive in the new setup - or that no one can possibly know what you've done. But you're going to create, just the same. You're going to give God another chance, so to speak.

'Maybe I just want to live - but the world could be worse. In twenty million different ways, it could be worse. A fellow named Wilder once wrote a play called The Skin of Our Teeth. Maybe you've read it. It's thesis was that Mankind survived by just that skin of their teeth. No, I'm not going to give you a speech about the Ice Age nearly wiping us out. I don't know enough. I'm not even going to talk about the Greeks winning at Marathon; the Arabs being defeated at Tours; the Mongols turning back at the last minute without even being defeated -because I'm no historian.

'But take the Twentieth Century. The Germans were stopped at the Marne twice in World War I. Dunkirk happened in World War II, and somehow the Germans were stopped at Moscow and Stalingrad. We could have used the atom bomb in the last war and we didn't, and just when it looked as if both sides would have to, the Great Compromise happened - just because General Bruce was delayed in taking off from the Ceylon airfield long enough to receive the message directly. One after the other, just like that, all through history - lucky breaks. For every "if" that didn't come true that would have made wonder-men of all of us if it had, there were twenty "ifs" that didn't come true that would have brought disaster to all of us if they had.

'You're gambling on that one-in-twenty chance - gambling every life on Earth. And you've succeeded, too, because Ty-wood did send that text back.'

He ground out that last sentence, and opened his fist, so that Boulder could fall out and back into his chair.

And Boulder laughed.

'You fool,' he gasped, bitterly, 'How close you can be and yet how widely you can miss the mark. Tywood did send his book back, then? You are sure of that?'

'No chemical textbook in Greek was found on the scene,' said the Boss, grimly, 'and millions of calories of energy had disappeared. Which doesn't change the fact, however, that we have two and a half weeks in which to - make things interesting for you.'

'Oh, nonsense. No foolish dramatics, please. Just listen to me, and try to understand. There were Greek philosophers once, named Leucippus and Democritus, who evolved an atomic theory. All matter, they said, was composed of atoms. Varieties of atoms were distinct and changeless and by their different combinations with each other formed the various substances found in nature. That theory was not the result of experiment or observation. It came into being, somehow, full-grown.

'The didactic Roman poet Lucretius, in his "De Rerum Natura," - "On the Nature of Things" - elaborated on that theory and throughout manages to sound startlingly modern.

'In Hellenistic times, Hero built a steam engine and weapons of war became almost mechanized. The period has been referred to as an abortive mechanical age, which came to nothing because, somehow, it neither grew out of nor fitted into its social and economic milieu. Alexandrian science was a queer and rather inexplicable phenomenon.

'Then one might mention the old Roman legend about the books of the Sibyl that contained mysterious information direct from the gods -

'In other words, gentlemen, while you are right that any change in the course of past events, however trifling, would have incalculable consequences, and while I also believe that you are right in supposing that any random change is much more likely to be for the worse than for the better, I must point out that you are nevertheless wrong in your final conclusions.

'Because this is the world in which the Greek chemistry text was sent back.

'This has been a Red Queen's race, if you remember your "Through the Looking Glass." In the Red, Queen's country, one had to run as fast as one could merely to stay in the same place. And so it was in this case! Tywood may have thought he was creating a new world, but it was I who prepared the translations, and I took care that only such passages as would account for the queer scraps of knowledge the ancients apparently got from nowhere would be included.

'And my only intention, for all my racing, was to stay in the same place.'

Three weeks passed; three months; three years. Nothing happened. When nothing happens, you have no proof. We gave up trying to explain, and we ended, the Boss and I, by doubting it ourselves.

The case never ended. Boulder could not be considered a criminal without being considered a world savior as well, and vice versa. He was ignored. And in the end, the case was neither solved, nor closed out; merely put in a file all by itself, under the designation '?' and buried in the deepest vault in Washington.

The Boss is in Washington now; a big wheel. And I'm Regional Head of the Bureau.

Boulder is still assistant professor, though. Promotions are slow at the University.

The Red Queen's Race,' my fifty-eighth story, was the first to be written by Dr. Asimov.

In September I began another story, 'Mother Earth,' and submitted it to Campbell on October 12, 1948. After a comparatively small revision of the ending, he took that one, too.

Mother Earth

'But can you be certain? Are you sure that even a professional historian can always distinguish between victory and defeat?'

Gustav Stein, who delivered himself of that mocking question with a whiskered smile and a gentle wipe at the gray moustache from the neighborhood of which he had just removed an empty glass, was not an historian. He was a physiologist.

But his companion was an historian, and he accepted the gentle thrust with a smile of his own.

Stein's apartment was, for Earth, quite luxurious. It lacked the empty privacy of the Outer Worlds, of course, since from its window there stretched outward a phenomenon that belonged only to the home planet - a city. A large city, full of people, rubbing shoulders, mingling sweat -

Nor was Stein's apartment fitted with its own power and its own utility supply. It lacked even the most elementary quota of positronic robots. In short, it lacked the dignity of self-sufficiency, and like all things on Earth, it was merely part of a community, a pendant unit of a cluster, a portion of a mob.

But Stein was an Earthman by birth and used to it. And after all, by Earth standards the apartment was still luxurious.

It was just that looking outward through the same windows before which lay the city, one could see the stars and among them the Outer Worlds, where there were no cities but only gardens; where the lawns were streaks of emerald, where all human beings were kings, and where all good Earthmen earnestly and vainly hoped to go some day.

Except for a few who knew better - like Gustav Stein.

The Friday evenings with Edward Field belonged to that class of ritual which comes with age and quiet life. It broke the week pleasantly for two elderly bachelors, and gave them an innocuous reason to linger over the sherry and the stars. It took them away from the crudities of life, and, most of all, it let them talk.

Field, especially, as a lecturer, scholar and man of modest means quoted chapter and verse from his still uncompleted history of Terrestrian Empire,...,

'I wait for the last act,' he explained. Then I can call it the "Decline and Fall of Empire" and publish it.'

'You must expect the last act to come soon, then.'

'In a sense, it has come already. It is just that it is best to wait for all to recognize that fact. You see, there are three times when an Empire or an Economic System or a Social Institution falls, you skeptic -'

Field paused for effect and waited patiently for Stein to say, 'And those times are?'

'First,' Field ticked off a right forefinger, 'there is the time when just a little nub shows up that points an inexorable way to finality. It can't be seen or recognized until the finality arrives, when the original nub becomes visible to hindsight.'

'And you can tell what that little nub is?'

'I think so, since I already have the advantage of a century and a half of hindsight. It came when the Sirian sector colony, Aurora, first obtained permission of the Central Government at Earth to introduce positronic robots into their community life. Obviously, looking back at it, the road was clear for the development of a thoroughly mechanized society based upon robot labor and not human labor. And it is this mechanization that has been and will yet be the deciding factor in the struggle between the Outer Words and Earth.'

'It is?' murmured the psychologist. 'How infernally clever you historians are. What and where is the second time the Empire fell?'

The second point in time,' and Fiejd gently bent his right middle finger backward, 'arrives when a signpost is raised for the expert so large and plain that it can be seen even without the aid of perspective. And that point has been passed, too, with the first establishment of an immigration quota against Earth by the Outer Worlds. The fact that Earth found itself unable to prevent an action so obviously detrimental to itself was a shout for all to hear, and that was fifty years ago.'

'Better and better. And the third point?'

The third point?' Down went the ring finger. That is the least important. That is when the signpost becomes a wall with a huge "The End" scrawled upon it. The only requirement for knowing that the end has come, then, is neither perspective nor training, but merely the ability to listen to the video.'

'I take it that the third point in time has not yet come.'

'Obviously not, or you would not need to ask. Yet it may come soon; for instance, if there is war.'

'Do you think there will be?'

Field avoided commitment. 'Times are unsettled, and a good deal of futile emotion is sweeping Earth on the immigration question. And if there should be a war, Earth would be defeated quickly and lastingly, and the wall would be erected.'

'Can you be certain? Are you sure that even a professional historian can always distinguish between victory and defeat?'

Field smiled. He said: 'You may know something I do not. For instance, they talk about something called the "Pacific Project."'

'I never heard of it.' Stein refilled the two glasses, 'Let us speak of others things.'

He held up his glass to the broad window so that the far stars flickered rosily in the clear liquid and said: 'To a happy ending to Earth's troubles.'

Field held up his own, 'To the Pacific Project.'

Stein sipped gently and said: 'But we drink to two different things.'

'Do we?'

It is quite difficult to describe any of the Outer Worlds to a native Earthman, since it is not so much a description of a world that is required as a description of a state of mind. The Outer Worlds - some fifty of them, originally colonies, later domininions, later nations - differ extremely among themselves in a physical sense. But the state of mind is somewhat the same throughout.

It is something that grows out of a world not originally congenial to mankind, yet populated by the cream of the difficult, the different, the daring, the deviant.

If it is to be expressed in a word, that word is 'individuality.'

There is the world of Aurora, for instance, three parsecs from Earth. It was the first planet settled outside the Solar System, and represented the dawn of interstellar travel. Hence its name.

It had air and water to start with, perhaps, but on Earthly standards it was rocky and infertile. The plant life that did exist, sustained by a yellow-green pigment completely unrelated to chlorophyll and not as efficient, gave the comparalively fertile regions a decidedly bilious and unpleasant appearance to unaccustomed eyes. No animal life higher than unicellular, and the equivalent of bacteria as well, were present. Nothing dangerous, naturally, since the two biological systems, of Earth and Aurora, were chemically unrelated,

Aurora became, quite gradually, a patchwork. Grains and fruit trees came first; shrubs, flowers and grass afterward. Herds of livestock followed. And, as if it were necessary to prevent too close a copy of the mother planet, positronic robots also came to build the mansions, carve the landscapes, lay the power units. In short, to do the work, and turn the planet green and human.

There was the luxury of a new world and unlimited mineral resources. There was the splendid excess of atomic power laid out on new foundations with merely thousands, or, at most, millions, not billions, to service. There was the vast flowering of physical science, in worlds where there was room for it.

Take the home of Franklin Maynard, for instance, who, with his wife, three children, and twenty-seven robots, lived on an estate more than forty miles away, in distance, from the nearest neighbor. Yet by community-wave he could, if he wished, share the living room of any of the seventy-five million on Aurora - with each singly; with all simultaneously.

Maynard knew every inch of his valley. He knew just where it ended, sharply, and gave way to the alien crags, along whose undesirable slopes the angular, sharp leaves of the native furze clung sullenly - as if in hatred of the softer matter that had usurped its place in the sun.

Maynard did not have to leave that valley. He was a deputy in the Gathering, and a member of the Foreign Agents Committee, but he could transact all business but the most extremely essential, by community-wave, without ever sacrificing that precious privacy he had to have in a way no Earthman could understand.

Even the present business could be performed by community-wave. The man, for instance, who sat with him in his living room, was Charles Hijkman, and he, actually, was sitting in his own living room on an island in an artificial lake stocked with fifty varieties of fish, which happened to be twenty-five miles distant, in space.