In twenty years we had found no trace of life but a few degenerate plants. No lunar civilization, whatever its doom, could have left but a single token of its existence.

  I looked at the shining pyramid again, and the more remote it seemed from anything that had to do with the Moon. And suddenly I felt myself shaking with a foolish, hysterical laughter, brought on by excitement and overexertion: for I had imagined that the little pyramid was speaking to me and was saying: "Sorry, I'm a stranger here myself."

  It has taken us twenty years to crack that invisible shield and to reach the machine inside those crystal walls. What we could not understand, we broke at last with the savage might

  of atomic power and now I have seen the fragments of the lovely, glittering thing I found up there on the mountain.

  They are meaningless. The mechanisms—if indeed they are mechanisms—of the pyramid belong to a technology that lies far beyond our horizon, perhaps to the technology of paraphysical forces.

  The mystery haunts us all the more now that the other planets have been reached and we know that only Earth has ever been the home of intelligent life in our Universe. Nor could any lost civilization of our own world have built that machine, for the thickness of the meteoric dust on the plateau has enabled us to measure its age. It was set there upon its mountain before life had emerged from the seas of Earth.

  When our world was half its present age, something from the stars swept through the Solar System, left this token of its passage, and went again upon its way. Until we destroyed it, that machine was still fulfilling the purpose of its builders; and as to that purpose, here is my guess.

  Nearly a hundred thousand million stars are turning in the circle of the Milky Way, and long ago other races on the worlds of other suns must have scaled and passed the heights that we have reached. Think of such civilizations, far back in time against the fading afterglow of Creation, masters of a Universe so young that life as yet had come only to a handful of worlds. Theirs would have been a loneliness we cannot imagine, the loneliness of gods looking out across infinity and finding none to share their thoughts.

  They must have searched the star clusters as we have searched the planets. Everywhere there would be worlds, but they would be empty or peopled with crawling, mindless things. Such was our own Earth, the smoke of the great volcanoes still staining the skies, when that first ship of the peoples of the dawn came sliding in from the abyss beyond Pluto. It passed the frozen outer worlds, knowing that life could play no part in their destinies. It came to rest among the inner planets, warming themselves around the fire of the Sun and waiting for their stories to begin.

  Those wanderers must have looked on Earth, circling safely in the narrow zone between fire and ice, and must have guessed that it was the favorite of the Sun's children. Here, in the distant future, would be intelligence; but there were countless stars before them still, and they might never come this way again.

  So they left a sentinel, one of millions they have scattered throughout the Universe, watching over all worlds with the promise of life. It was a beacon that down the ages has been patiently signaling the fact that no one had discovered it.

  Perhaps you understand now why that crystal pyramid was set upon the Moon instead of on the Earth. Its builders were not concerned with races still struggling up from savagery. They would be interested in our civilization only if we proved our fitness to survive—by crossing space and so escaping from the Earth, our cradle. That is the challenge that all intelligent races must meet, sooner or later. It is a double challenge, for it depends in turn upon the conquest of atomic energy and the last choice between life and death.

  Once we had passed that crisis, it was only a matter of time before we found the pyramid and forced it open. Now its signals have ceased, and those whose duty it is will be turning their minds upon Earth. Perhaps they wish to help our infant civilization. But they must be very, very old, and the old are often insanely jealous of the young.

  I can never look now at the Milky Way without wondering from which of those banked clouds of stars the emissaries are coming. If you will pardon so commonplace a simile, we have set off the fire alarm and have nothing to do but to wait.

  I do not think we will have to wait for long.

  London December 1948

  Transience

  The forest, which came almost to the edge of the beach, climbed away into the distance up the flanks of the low, misty hills. Underfoot, the sand was coarse and mixed with myriads of broken shells. Here and there the retreating tide had left long streamers of weed trailed across the beach. The rain, which seldom ceased, had for the moment passed inland, but ever and again large, angry drops would beat tiny craters in the sand.

  It was hot and sultry, for the war between sun and rain was never-ending. Sometimes the mists would lift for a while and the hills would stand out clearly above the land they guarded. These hills arced in a semicircle along the bay, following the line of the beach, and beyond them could sometimes be seen, at an immense distance, a wall of mountains lying beneath perpetual clouds. The trees grew everywhere, softening the contours of the land so that the hills blended smoothly into each other. Only in one place could the bare, uncovered rock be seen, where long ago some fault had weakened the foundations of the hills, so that for a mile or more the sky line fell sharply away, drooping down to the sea like a broken wing.

  Moving with the cautious alertness of a wild animal, the child came through the stunted trees at the forest's edge. For

  a moment he hesitated; then, since there seemed to be no danger, walked slowly out onto the beach.

  He was naked, heavily built, and had coarse black hair tangled over his shoulders. His face, brutish though it was, might almost have passed in human society, but the eyes would have betrayed him. They were not the eyes of an animal, for there was something in their depths that no animal had ever known. But it was no more than a promise. For this child, as for all his race, the light of reason had yet to dawn. Only a hairsbreadth still separated him from the beasts among whom he dwelt.

  The tribe had not long since come into this land, and he was the first ever to set foot upon that lonely beach. What had lured him from the known dangers of the forest into the unknown and therefore more terrible dangers of this new element, he could not have told even had he possessed the power of speech. Slowly he walked out to the water's edge, always with backward glances at the forest behind him; and as he did so, for the first time in all history, the level sand bore upon its face the footprints it would one day know so well.

  He had met water before, but it had always been bounded and confined by land. Now it stretched endlessly before him, and the sound of its laboring beat ceaselessly upon his ears.

  With the timeless patience of the savage, he stood on the moist sand that the water had just relinquished, and as the tide line moved out he followed it slowly, pace by pace. When the waves reached toward his feet with a sudden access of energy, he would retreat a little way toward the land. But something held him here at the water's edge, while his shadow lengthened along the sands and the cold evening wind began to rise around him.

  Perhaps into his mind had come something of the wonder of the sea, and a hint of all that it would one day mean to man. Though the first gods of his people still lay far in the future, he felt a dim sense of worship stir within him. He knew that he was now in the presence of something greater than all the powers and forces he had ever met.

  The tide was turning. Far away in the forest, a wolf howled once and was suddenly silent. The noises of the night were rising around him, and it was time to go.

  Under the low moon, the two lines of footprints interlaced across the sand. Swiftly the oncoming tide was smoothing them away. But they would return in their thousands and millions, in the centuries yet to be.

  The child playing among the rock pools knew nothing of the forest that had once ruled all the land around him. It had left no trace of its existence. As ephemeral as the
mists that had so often rolled down from the hills, it, too, had veiled them for a little while and now was gone. In its place had come a checkerboard of fields, the legacy of a thousand years of patient toil. And so the illusion of permanence remained, though everything had altered except the line of the hills against the sky. On the beach, the sand was finer now, and the land had lifted so that the old tide line was far beyond the reach of the questing waves.

  Beyond the sea wall and the promenade, the little town was sleeping through the golden summer day. Here and there along the beach, people lay at rest, drowsy with heat and lulled by the murmur of the waves.

  Out across the bay, white and gold against the water, a great ship was moving slowly to sea. The boy could hear, faint and far away, the beat of its screws and could still see the tiny figures moving upon its decks and superstructure. To the child—and not to him alone—it was a thing of wonder and beauty. He knew its name and the land to which it was steaming; but he did not know that the splendid ship was both the last and greatest of its kind. He scarcely noticed, almost lost against the glare of the sun, the thin white vapor trails that spelled the doom of the proud and lovely giant.

  Soon the great liner was no more than a dark smudge on the horizon, and the boy turned again to his interrupted play. to the tireless building of his battlements of sand. In the west

  the sun was beginning its long decline, but the evening was still far away.

  Yet it came at last, when the tide was returning to the land. At his mother's words, the child gathered up his playthings and, wearily contented, began to follow his parents back to the shore. He glanced once only at the sand castles he had built with such labor and would not see again. Without regret he left them to the advancing waves, for tomorrow he would return and the future stretched endlessly before him.

  That tomorrow would not always come, either for himself or for the world, he was still too young to know.

  And now even the hills had changed, worn away by the weight of years. Not all the change was the work of Nature, for one night in the long-forgotten past something had come sliding down from the stars, and the little town had vanished in a spinning tower of flame. But that was so long ago that it was beyond sorrow or regret. Like the fall of fabled Troy or the overwhelming of Pompeii, it was part of the irremediable past and could rouse no pity now.

  On the broken sky line lay a long metal building supporting a maze of mirrors that turned and glittered in the sun. No one from an earlier age could have guessed its purpose. It was as meaningless as an observatory or a radio station would have been to ancient man. But it was neither of these things.

  Since noon, Bran had been playing among the shallow pools left by the retreating tide. He was quite alone, though the machine that guarded him was watching unobtrusively from the shore. Only a few days ago, there had been other children playing beside the blue waters of this lovely bay. Bran sometimes wondered where they had vanished, but he was a solitary child and did not greatly care. Lost in his own dreams, he was content to be left alone.

  In the last few hours he had linked the tiny pools with an intricate network of waterways. His thoughts were very far from Earth, both in space and time. Around him now were

  the dull, red sands of another world. He was Cardenis, prince of engineers, fighting to save his people from the encroaching deserts. For Bran had looked upon the ravaged face of Mars; he knew the story of its long tragedy and the help from Earth that had come too late.

  Out to the horizon the sea was empty, untroubled by ships, as it had been for ages. For a little while, near the beginning of time, man had fought his brief war against the oceans of the world. Now it seemed that only a moment lay between the coming of the first canoes and the passing of the last great Megatheria of the seas.

  Bran did not even glance at the sky when the monstrous shadow swept along the beach. For days past, those silver giants had been rising over the hills in an unending stream, and now he gave them little thought. All his life he had watched the great ships climbing through the skies of Earth on their way to distant worlds. Often he had seen them return from those long journeys, dropping down through the clouds with cargoes beyond imagination.

  He wondered sometimes why they came no more, those returning voyagers. All the ships he saw now were outward bound; never one drove down from the skies to berth at the great port beyond the hills. Why this should be, no one would tell him. He had learned not to speak of it now, having seen the sadness that his questions brought.

  Across the sands the robot was calling to him softly. "Bran," came the words, echoing the tones of his mother's voice, "Bran—it's time to go."

  The child looked up, his face full of indignant denial. He could not believe it. The sun was still high and the tide was far away. Yet along the shore his mother and father were already coming toward him.

  They walked swiftly, as though the time were short. Now and again his father would glance for an instant at the sky, then turn his head quickly away as if he knew well that there was nothing he could hope to see. But a moment later he would look again.

  Stubborn and angry, Bran stood at bay among his canals and lakes. His mother was strangely silent, but presently his father took him by the hand and said quietly, "You must come with us, Bran. It's time we went."

  The child pointed sullenly at the beach. "But it's too early. I haven't finished."

  His father's reply held no trace of anger, only a great sadness. "There are many things, Bran, that will not be finished now."

  Still uncomprehending, the boy turned to his mother.

  "Then can I come again tomorrow?"

  With a sense of desolating wonder, Bran saw his mother's eyes fill with sudden tears. And he knew at last that never again would he lay upon the sands by the azure waters; never again would he feel the tug of the tiny waves about his feet. He had found the sea too late, and now must leave it forever. Out of the future, chilling his soul, came the first faint intimation of the long ages of exile that lay ahead.

  He never looked back as they walked silently together across the clinging sand. This moment would be with him all his life, but he was still too stunned to do more than walk blindly into a future he could not understand.

  The three figures dwindled into the distance and were gone. A long while later, a silver cloud seemed to lift above the hills and move slowly out to sea. In a shallow arc, as though reluctant to leave its world, the last of the great ships climbed toward the horizon and shrank to nothingness over the edge of the Earth.

  The tide was returning with the dying day. As though its makers still walked within its walls, the low metal building upon the hills had begun to blaze with light. Near the zenith, one star had not waited for the sun to set, but already burned with a fierce white glare against the darkling sky. Soon its companions, no longer in the scant thousands that man had once known, began to fill the heavens. The Earth was now near the center of the Universe, and whole areas of the sky were an unbroken blaze of light.

  But rising beyond the sea in two long curving arms, something black and monstrous eclipsed the stars and seemed to cast its shadow over all the world. The tentacles of the Dark Nebula were already brushing against the frontiers of the Solar System. . . .

  In the east, a great yellow moon was climbing through the waves. Though man had torn down its mountains and brought it air and water, its face was the one that had looked upon Earth since history began, and it was still the ruler of the tides. Across the sand the line of foam moved steadily onward, overwhelming the little canals and planing down the tangled footprints.

  On the sky line, the lights in the strange metal building suddenly died, and the spinning mirrors ceased their moonlight glittering. From far inland came the blinding flash of a great explosion, then another, and another fainter yet.

  Presently the ground trembled a little, but no sound disturbed the solitude of the deserted shore.

  Under the level light of the sagging moon, beneath the myriad sta
rs, the beach lay waiting for the end. It was alone now, as it had been at the beginning. Only the waves would move, and but for a little while, upon its golden sands.

  For man had come and gone.

  London March 1947

  The Star

  It is three thousand light-years to the Vatican. Once, I believed that space could have no power over faith, just as I believed that the heavens declared the glory of God's handiwork. Now I have seen that handiwork, and my faith is sorely troubled. I stare at the crucifix that hangs on the cabin wall above the Mark VI Computer, and for the first time in my life I wonder if it is no more than an empty symbol.

  I have told no one yet, but the truth cannot be concealed. The facts are there for all to read, recorded on the countless miles of magnetic tape and the thousands of photographs we are carrying back to Earth. Other scientists can interpret them as easily as I can, and I am not one who would condone that tampering with the truth which often gave my order a bad name in the olden days.

  The crew were already sufficiently depressed: I wonder how they will take this ultimate irony. Few of them have any religious faith, yet they will not relish using this final weapon in their campaign against me—that private, good-natured, but fundamentally serious war which lasted all the way from Earth. It amused them to have a Jesuit as chief astrophysicist: Dr. Chandler, for instance, could never get over it. (Why are medical men such notorious atheists?) Sometimes he would meet me on the observation deck, where the lights

  are always low so that the stars shine with undiminished glory. He would come up to me in the gloom and stand staring out of the great oval port, while the heavens crawled slowly around us as the ship turned end over end with the residual spin we had never bothered to correct.