Abruptly, it was snatched from his hand, and in seconds Moon-Watcher was halfway up the cliff, carrying his prize between his teeth. Patiently, Clindar started to slice away at the carcass once more, waiting for the next move. It came within the hour, when Moon-Watcher returned for a second helping. This time, Graypate and Broken Fang followed him part of the way down the cliff face, anxious to see how it was done.

  So the experiment in primitive diplomacy continued, day after day-sometimes in the morning before the hominids had left their cave, sometimes in the evening as they returned from the day's foraging. By the end of a week, Clindar had become accepted as an honorary member of the tribe. They were completely unafraid of him, and would squat in a circle watching his actions from a few feet away. Some of the infants would scamper over and touch him, until scolded by their mothers; but the adults still avoided direct contact. They were inquisitive, but not yet friendly.

  To Clindar it was a weird, almost unreal existence, this daily switching between two worlds a million years apart. While his colleagues were probing the planet with the most advanced instruments of their science, he was mentally identifying himself with creatures who had barely reached the dawn of reason. He had to see through their eyes, remember the limitations of their clumsy fingers, imagine the slow processes of their brains when they were confronted with something new. Fortunately, there was the experience of others to guide him; when he was aboard the scoutship, he would search the records of the past, learning what earlier expeditions had done, on other worlds. He could profit from their successes, and avoid their mistakes.

  Because speech still lay a million years in the future, the only way to instruct these creatures was by example. And because his people excelled in anything they turned their minds to, Clindar was soon the most efficient hunter on the planet. He was surprised, and a little disturbed, to find how much he enjoyed it. The ancient instincts had not wholly died, even though it had been a hundred thousand generations since they had last been given rein.

  His favorite weapon was the thighbone of one of the larger antelopes; with its knobbly end, it formed a perfect natural club, much superior to any branch that could be wrenched off a tree. With a single well-placed blow it could kill animals up to the size of the hominids themselves, and it could drive off creatures that were far larger. Clindar was anxious to prove this, and had thought of staging a demonstration. As it turned out, his wish was granted without any deliberate planning.

  The horde-it could not yet be granted the name of tribe-had now completely identified him with food, and the males were ready to follow him wherever he went. Even those females who were not burdened with infants would sometimes stop gathering leaves and fruit to accompany him, in the hope of profiting from his success.

  They found the dead zebra only a few hundred yards from the scoutship, surrounded by the hyenas that had run it down. There were six of the mangy, unprepossessing scavengers worrying the carcass; confident that nothing smaller than a lion could disturb them, they continued their feasting as Clindar approached. Behind his back he could hear his pupils chattering nervously as they kept their distance.

  The hyenas looked at Clindar warily, snarling and holding their ground, as he came nearer. He was the first biped they had ever seen-indeed, the only biped in all this world-but his strangeness did not alarm them. They were certain that they could protect their spoils.

  A second later, they were not so sure. Clindar advanced on them like a whirlwind, a club in each hand-for he was completely ambidextrous-and started raining blows on the startled beasts. Too astonished to fight back, they fled, yelping hideously; then one of them regained his courage, spun around, and launched himself straight at Clindar's head.

  That was good; it must not seem too easy, or the hominids would put too great a faith in these primitive weapons, and get themselves into disastrous situations. They must learn that a club would not make them invincible, and that the outcome of a fight would still depend on their own skill and strength.

  Nevertheless, Clindar cheated, it was not really a fair demonstration, though it served its purpose admirably. He was far more powerful and better coordinated than these clumsy ape-men, and in an emergency he could move with a speed which very few animals on this world could match. Moreover, he was completely protected by the flexible yet incredibly tough film that insulated him from the microscopic killers that teemed in air and soil. The hyena did not really have a chance.

  Clindar had already moved aside as it went hurtling by him, drifting past in slow motion to his accelerated senses. He caught it one terrific blow with the club as it sailed by-misjudging his strength, because the bone splintered and snapped and he was left holding the stump in his hand. But it did not matter, the hyena was dead before it reached the ground. The others, who had turned to watch the fight and were prowling hopefully in the near distance, did not wait for a further demonstration.

  During the fight, the hominids had also kept their distance, but at least they had not been scared away. Now they approached with a kind of nervous eagerness, their attention equally divided between Clindar and his victim.

  Moon-Watcher, always in the forefront, reached him first. He edged over to the slain hyena, put out a cautious paw, touched the body, and quickly withdrew. Twice he repeated this, until he was convinced that the animal was really dead. Then his jaw dropped in a comical expression of astonishment, and he stared at Clindar as if he could not believe his eyes.

  Clindar held out the second, unbroken dub in his right hand, and waited. This was the moment; no better one would ever come. If Moon-Watcher had not learned the lesson now, he would never do so.

  The hominid came slowly toward him, then squatted down only five feet away; he had never approached so closely before. Holding his head slightly on one side in an attitude of intense concentration, he stared at the bone held rigidly in Clindar's hand. Then he reached out a paw and touched the crude club.

  His fingers grasped the end, and tugged gently at it. Clindar held firm for a moment, then released his grip.

  Moon-Watcher drew the bone away from him, looked at it intently, then began to sniff and nibble at it. A spasm of disappointment shot through Clindar's mind; the lesson was already forgotten. This was just another morsel of food-not a key to the future, a tool that could lead to the mastery of this world, and of many others.

  Then Moon-Watcher suddenly remembered. He jumped to his feet, and began to dance around waving the club in his right paw. As long as he kept moving, he could rear almost upright; only when he stood still did he have to use his free forelimb as a support. He had already begun to make the awesome and irrevocable transition from quadruped to biped.

  The little dance lasted about five seconds; then Moon-Watcher shot off on a tangent. He raced toward the dead hyena in such a frenzy of excitement that his companions, who had already started to quarrel over the feast, scattered in fright.

  Awkwardly, but with an energy that made up for his lack of skill, Moon-Watcher began to pound the carcass with his club, while the others looked on with awed astonishment. Clindar alone understood what was happening, and knew that this world had come to a turning point in time. To the most promising of its creatures, he had given the first tool; and the history of yet another race had begun.

  FAREWELL TO EARTH

  During the next five years, as the scoutships drifted far and wide over the face of the planet gathering thousands of specimens and millions of items of information, Clindar revisited the hominids many times. He never went hunting with them again; they had learned that lesson with astonishing-indeed, with ominous-speed, and all the males now knew how to use clubs when the need arose. Instead he had tried to introduce other tools, of which the most important were stone knives and hammers.

  These small hand tools, crude though they might appear at first sight, represented a gigantic leap forward in technology. They multiplied the efficiency-and therefore the chance of survival-of their users many times. With a prop
erly shaped flint one could dig up tough roots and hack off succulent branches which would otherwise be exhausting and laborious to collect. And a small, round pebble that fitted the hand nicely could split bones to get at the marrow, or crack animal skulls to reach the tenderest and most well-protected of all meat.

  One day, if all went well, the hominids would not only use tools-they would make them; and they would make them of metal and of plastic and, in the end, of pure fields of force. But how they would use those tools-whether for good or for evil-was beyond prediction, and to be revealed only by the passing of the ages.

  They had been given their initial impetus, and that was all that one could, or should, do for a species at this level of intelligence; the rest was up to them. The outcome might yet be disastrous, as it had often been in the past. Failures could not be avoided, but they could be expunged; if one world was lost, there were many others. For Clindar's race, driven by impulses long buried in their own infancy, were gardeners in the field of stars. They sowed, and often they reaped. But sometimes they had to weed.

  For the last time, Clindar stood on the African plain, brooding over his experiment with destiny. Above him loomed the globe of the scoutship, already throbbing with the energies that would soon carry him up to the lonely heights of space. And on his shoulder, completely unafraid, sat one of the little ape-children, searching hopefully for lice and salt crystals in the folds of his outer clothing. Clindar had long since been able to discard his protective envelope; he was now immune to the micro-fauna of this world, and carried nothing in his own body that could destroy the life around him.

  A few yards away, the mother hominid was plucking berries; she had ignored her child completely, as if quite confident that it was in safe hands. She could never guess. thought Clindar, how much this little creature's chances of survival had improved. The tribe had prospered, thanks to the tools and weapons he had given it; no longer was it starving and defenseless. Even the big cats had begun to avoid these animals whose forelimbs, though they had no claws, could inflict such stinging pain.

  A series of musical notes sounded from the communicator at Clindar's waist; his friends were growing impatient. He could not blame them; all these years they had remained insulated from this world, while he took the risks- and the rewards. Their turn would come later, on other planets, while he watched the instruments and recorders from the safety of the ship. Where was Moon- Watcher? Not far away, he was sure. He gave the three piercing whistles that the hominid had learned to recognize as his signal, and waited.

  A few minutes later, there was a rustling in the undergrowth, and Moon-Watcher emerged, carrying a small gazelle over his shoulder. He grimaced and chittered with pleasure at the sight of his friend, and started to lope toward him with the awkward but swift three-limbed gait he employed when one of his forepaws was holding something.

  In the last five years Moon-Watcher had matured and aged a good deal, and was now nearing the-doubtless violent-end of his short life. But he was in good condition, with only a few bald patches on his chest and thighs and he was well fed. He had lost his left ear in a fight with a hyena a few months ago, and that in itself was a sign of progress. None of his ancestors would have dreamed of competing with the snarling scavengers of the plains.

  Still carrying the infant on his shoulder, Clindar moved out from the shadow of the ship to meet his friend. Perhaps the baby was Moon-Watcher's; there was no way of telling, for mating among the hominids was completely promiscuous and stable family relations were still ages in the future. The infants were indiscriminately mothered by all the females, and cuffed out of the way by all the males.

  This open place would do well enough. Clindar reached out his hand toward Moon-Watcher, and waited. In the early days the hominid had avoided all contact, especially when he was carrying food, but now he was no longer in the least shy. Trustingly, he held out his free hand toward Clindar, and for the last time they touched across the gulfs that sundered them.

  Clindar tugged the hairy paw upward, so that MoonWatcher stood teetering on his hind legs. in the position his remote descendants must one day assume if they were ever to free their hands and their minds. He turned his face toward the ship, and gave the slight twist of the head that signified "now." The brief affirmative tone came from his communicator almost at once, and he let Moon- Watcher's hand drop back to the ground.

  Ages after the little hominid's bones had dissolved into dust this recording of their farewell would still exist, to be recalled whenever Clindar pleased. He would add others to it, in the years and the millennia that lay ahead, until the time came-if it ever did-when at last he was tired of the Universe, and of immortality.

  Silent as rising smoke, the bubble of the scoutship lifted from the African plain and dwindled into the sky. Moon-Watcher never saw it go; the gazelle he had killed now engaged his full attention. Soon he would forget his visitor-but not the gifts he had brought from the stars.

  And his descendants would use them, with ever increasing skill, until it was time for the next meeting.

  There was one small but important matter still to be arranged, and the ship landed briefly on the Moon to do it. In the lunar midnight, the cold rocks split and scattered as the traction fields tore into them, digging the cavity that would protect the Sentinel from all foreseeable accidents of time and space. The black tetrahedron was set upon its supporting apron, and then sealed off from the light of the sun and the light of the earth. The broken rock was poured back into place; in a few thousand years, the incessant rain of meteor dust would have hidden the scar completely.

  But the buried machine's magnetic signal would shout its presence to the empty sky, and any intelligence that came this way could not fail to observe it. If, ages hence, Moon-Watcher's descendants attained the freedom of space, they must pause here on the way to the stars, and those who had set them on the road would know that they were coming, and would prepare to welcome them.

  Or it might be that a culture would arise on this planet flourish briefly in the innocent belief that the universe revolved around it, and then sink back once more into the dim twilight of preconscious thought, rejoining the animal kingdom from which it had emerged. Such civilizations were too numerous to be counted, far less examined, in this galaxy of a hundred billion worlds. Though they might contain many marvels and hold much of interest, yet one had to pass them by. Indeed, few lasted long enough for a second visit; they were ephemeral flashes of intelligence, flickering like fireflies in the cosmic night.

  But once a species had begun to move out from its native world, and had become aware of the universe around it, it was worthy of attention. Only a space-faring culture could truly transcend its environment, and join others in giving a purpose to creation. Therefore such cultures had to be detected and cherished, when they merited it, which was not always the case. The sentinel beacons that now kept hopeful watch upon more than a million planets sometimes brought bad news as well as good.

  As the ship lifted from the heart of Tycho, Clindar caught one last glimpse of the blue-green globe hanging motionless in the lunar sky. Africa was turned toward him, warming itself in the rays of the hidden sun. He wished he could have stayed longer-a hundred years, at least-but new worlds were calling, far down the unimaginable convolutions of the Star Gate.

  It was unlikely that he would ever know the outcome of the chain reaction he had started here; the chances were that it would die out in a few generations, and leave no trace. In these early stages disease or changing climate or accident could so easily wipe out the glimmering, predawn intelligence, before it was strong enough to protect itself against the blind forces of the Universe.

  For if the stars and the galaxies had the least concern for mind, or the slightest awareness of its presence, that was yet to be proved.

  THE BIRTH OF HAL

  The movie 2001 has often been criticised as lacking human interest, and having no real characters-except HAL. In leaping straight from the Pleistocene
into space, Stanley Kubrick bypassed all the problems that would have been involved in developing the personal backgrounds of the astronauts, the political and cultural impact produced by the discovery of the monolith, and the general details of life at the beginning of the next century. We could have written a whole book about that; in fact, we did....

  And when we had done so, we realized that it was irrelevant to the main theme of the movie. To have developed all this background material-besides adding a couple of hours to the running time and several millions to the cost-would have thrown the whole story out of focus. So the novel contains only a few pages set on Earth, 2001 AD, while the film ignores the subject completely, and jumps straight into space.

  One of the problems facing any science-fiction writer who is aiming for the general public is how much to explain, and how much to take for granted. He must try not to leave his readers baffled, but at the same time must avoid those disguised lectures which are all too typical of the genre ("Now tell me, Professor...."). At one time, Stanley hoped to get around this problem-as far as the movie was concerned-by opening with a short documentary-type prelude, in which noted scientists and philosophers would establish the credibility of our theme. With this idea in mind, he sent Roger Caras around the world, to interview, on film, more than twenty authorities on space, computers, anthropology-even religion. They included the astronomers Harlow Shapley, Sir Bernard Lovell, Fred Whipple, Frank Drake; Dr. Margaret Mead (who was a space bug long before Sputnik) and the great Russian scientist A. I. Oparin, the first man to point out (in the 1920's) a plausible way in which life could arise from the simple chemicals of the primitive Earth.