Mind Webs - The Sentinel

0:30My word. Welcome to a half hour of mind ways. Thank you. area.

1:50The next time you see the full moon, high in the south, look carefully at its right hand edge and let your eye travel upward along the curve of the disc. Around about 2 o'clock you'll notice a small dark oval. Anyone with normal eyesight can find it quite easily. It's the great walled plane, one of the finest on the moon, known as a merry chrysalon, the sea of crises. 300 miles in diameter and almost completely surrounded by a ring of magnificent mountains, it had never been explored until we entered it in the late summer of 96. Our expedition was a large one, we had two heavy freighters which had flown our supplies and equipment from the main lunar base in the Mary's Aranatatus 500 miles away. There were also three small rockets which were intended for short range transport over regions which our surface vehicles couldn't cross. Luckily, most of the Mary Chrissium is very flat. There are none of the great crevices so common and so dangerous elsewhere and very few

2:53craters or mountains of any size. As far as we could tell, our powerful caterpillar tractors would have no difficulty in taking us wherever we wished to go. I was a geologist or a cellanologist if you want to be the Danny can charge to the group exploring the southern region of the sea. We had crossed 100 miles of it in a week, skirting the foothills of the mountains along the shore of what had once been the ancient sea, some thousand million years before. When life was beginning on earth, it was already dying here. The waters were retreating down the flanks of those dependous cliffs, retreating into the empty heart of the moon. Over the land which we were crossing, the tidal ocean had once been half a mile deep. And now the only trace of moisture was the horfrost one could sometimes find in caves which the serene sunlight never penetrated. We had begun our journey early in the slow lunar dawn and still had almost a week of earth time before nightfall.

3:55Half a dozen times a day we'd leave our vehicle and go outside in the spacesuits to hunt for interesting minerals or to place markers for the guidance of future travelers. It was an uneven full routine. There's nothing hazardous or even particularly exciting about lunar exploration. We could live comfortably for a month in our pressurized tractors and if we ran into trouble we could always radio for help and sit tight until one of the spaceships came to our rescue. I said just now that there was nothing exciting about lunar exploration but of course that isn't true. One could never grow tired of those incredible mountains, so much more rugged than the gentle hills of earth. We never knew as we mounted the capes and promenatories of that vanished sea. Most new splendors would be revealed to us. The whole southern curve of the Mary Chrissium is a vast delta where a score of rivers once found their way into the ocean fed perhaps by the torrential rains that must have lashed

4:55the mountains in the brief volcanic age when the moon was young. Each of these ancient valleys was an invitation, challenging us to climb into the unknown uplands beyond. We had a hundred miles still to cover and could only look longingly at the heights which others must scale. We kept earth time aboard the tractor and precisely at 2,200 hours the final radio message would be sent out to base and we would close down for the day. Outside the rocks would still be burning beneath the almost vertical sun but to us it was night until we awoke again eight hours later. And one of us would prepare breakfast and there would be a great buzzing of electric razors and someone would switch on the shortwave radio from earth. Indeed, when the smell of frying sausages began to fill the cabin, it was sometimes hard to believe that we were not back on our own world. Everything was so normal and only apart from the feeling of decreased weight and the unnatural slowness with which objects fell.

5:58It was my turn to prepare breakfast in the corner of the lane cabin that served as a galley. I can remember that moment quite vividly after all these years when the radio had just played one of my favorite melodies, the old well-shared David of the White Rock. And our driver was already outside in his base suit and speccing our caterpillar treads. And my assistant, Louis Garnet, was up forward in the control position in the Ainson-related entries in yesterday's vlog. As I stood by the frying pan waiting for the sausages to brown, I let my gaze wander idly over the mountain walls which covered the hole of the southern horizon, marching out of sight to east and west below the curve of the moon. They seemed only a mile or two from the tractor, but I knew that the nearest was twenty miles away. On the moon, of course, there is no loss of detail with distance. None of that almost imperceptible hazingness which softens and sometimes transfigures all far off things on earth.

6:58Those mountains were ten thousand feet high and they climbed steeply out of the plain as if ages ago some subterranean eruption had smashed them skyward through the molten crust. The base of even the nearest was hidden from sights by the steeply curving surface of the plain for the moon as a very little world. And from where I was standing, the horizon was only about two miles away. I lifted my eyes toward the peaks which no man had ever climbed, the peaks which before the coming of terrestrial life had watched the retreating ocean sink solemnly into their graves, taking with them the hope and the morning promise of a world. The sunlight was beating against those ramparts of the glare that hurt the eyes. Yet only a little way above them the stars were shining steadily in the sky, blacker than a winter midnight on earth. I was turning away when my eye caught a metallic glitter high on the ridge of a great promontory

8:00thrusting out into the sea thirty miles to the west. It was a dimensionless point of light as if a star had been clawed from the sky by one of those cruel peaks. And I imagined that some smooth rock surface was catching the sunlight and heliographing it straight into my eyes, such things were not uncommon. When the moon is in her second quarter observers on earth can sometimes see the great ranges in the oceanis prosa lera burning with a blue white ear of decences, the sunlight flashes when their slopes and leaps again from world to world. But I was curious to know what kind of rock could be shining so brightly up there. And I climbed into the observation turret in one hour four inch telescope round to the west. I could see just enough to tenderize me clear and sharp in the field of vision. The mountain peaks seemed only half a mile away. But whatever was catching the sunlight was still too small to be resolved.

9:04It seemed to have an elusive symmetry and the summit upon which it rested was curiously flat. I stared for a long time at that glittering enigma, straining my eyes into space until presently a smell of burning from the galley told me that our breakfast sausages had made their quarter million mile journey in vain. All that morning we argued our way across the merry chrisium while the western mountains weird higher in the sky. And when we were out prospecting in the space suits the discussion would continue over the radio. It was absolutely certain, like companions I queued, that there had never been any form of intelligent life on the moon. Only living things that had ever existed there were a few primitive plants and there's likely less degenerate ancestors. I knew that as well as anyone. But there are times when a scientist was not be afraid to make a fool of himself. And I said at last, listen, listen, I'm going up there if only for my own peace of mind.

10:07That mountains less than 12,000 feet high, that's only 2,000 under earth gravity. And I can make the trip in 20 hours at the outside. I've always wanted to go up into those hills anyway and this gives me an excellent chance. Well, Garnet said that if I didn't break my neck I'd be the laughing stock of the expedition when we got back to base and the mountain probably would be called Wilson's Folly. I told him firmly that I wasn't about to break my neck and after all who was the first man to climb Pico and Helikon. And he said, well, I was rather younger in those days and I responded that that was as good a reason as any for my going. We went to bed early that night after driving the tractor, two and a half a mile of the promontory. Garnet was coming with me in the morning, he was a good climber and had often been with me on such exploits before. Our driver was only too glad to be left in charge of the machine. At first sight those cliffs seemed completely unscalable but to anyone with a good head for

11:13heights climbing is easy on a world where all weights are only a sixth of their normal value. The real danger in lunar mountaineering lies in overconfidence. A 600 foot drop on the moon can kill you just as thoroughly as a hundred foot fall on earth. We made our first halt and a wide ledge about 4,000 feet above the plane. Climbing had not been very difficult but my limbs were stiff with the unaccustomed effort and I was glad of the rest. We could see the tractors, a tiny metal insect far down at the foot of the cliff and we reported our progress to the driver before starting on the next descent. Inside our suits it was comfortably cool for the refrigeration units who were fighting the fear of sun and carrying away the body heat of our exertions. We seldom spoke to each other except to pass climbing instructions and to discuss our best plan of descent. I don't know what Garnett was thinking, probably that this was the craziest goose chase he

12:19had ever embarked upon. I more than half agreed with him but the joy of climbing the knowledge that no man had ever gone this way before and the exhilaration of the steadily widening landscape gave me all the reward I needed. I don't think I was particularly excited when I saw in front of us the wall of rock. I had first inspected through the telescope from 30 miles away. It would level off about 50 feet above our heads and there on the plateau would be the thing that had lured me over these barren wastes. It was almost certainly nothing more than a boulder splintered ages ago by a falling meteor and with its cleavage playing still fresh and bright in this incorruptible unchanging silence. There were no handholds on the rock face. We had to use a grapple. My tired arms seemed to gain new strength as I swung the three pronged metal anchor around my head and sent it sailing up towards the stars.

13:19The first time it broke loose and came falling slowly back and we pulled the rope. On the third attempt the prongs gripped firmly and our combined weights could not shift it. Garnet looked at me anxiously. I could tell that he wanted to go first but I smiled back at him through the glass of my helmet and shook my head. Slowly taking my time I began the final ascent. Even with my space suit I weighed only 40 pounds here so I pulled myself up hand over hand without bothering to use my feet. At the rim I paused and waved to my companion and I scrambled over the edge and stood upright staring ahead of me. You must understand that until this very moment I had been almost completely convinced that there could be nothing strange or unusual for me to find here, almost but not quite. It was that haunting doubt that it driven me forward. Well it was a doubt no longer but the haunting had scarcely begun.

14:22I was standing on a plateau perhaps a hundred feet across that once been smooth, too smooth to be natural but falling meteors had pitted and scored its surface through immeasurable eons. It had been leveled to support a glittering, roughly pyramidal structure. Twice as high as a man that was set in the rock like a gigantic many fasted jewel. Probably no emotion at all filled my mind in those first few seconds. Then I felt a great lifting of my heart and a strange inexpressible joy. For I loved the moon and now I knew that the creeping moss of Aristarchus and Aristophanes was not the only life she had brought forth in her youth. The old discredited dream of the first explorers was true. There had, after all, been a lunar civilization and I was the first to find it. I had come perhaps a hundred million years too late did not distress me.

15:25It was enough to have come at all. My mind was beginning to function normally to analyze and to ask questions. Was this a building, a shrine or something for which my language had no name? If a building, then why was it erected in so uniquely inaccessible a spot? I wondered if it might be a temple and I could picture the adips of some strange priesthood calling on their gods to preserve them as the life of the moon have to with the dying oceans and calling on their gods in vain. I took a dozen steps forward to examine the thing more closely but some sense of caution kept me from going to near. I knew a little of archaeology and tried to guess the cultural level of the civilization that must have smoothed this mountain and raised the glittering mirror surfaces that still dazzled my eyes. The Egyptians could have done it, I thought, if their workmen had possessed whatever strange

16:25materials these far more ancient architects had used, because of the things smallness. It did not occur to me that I might be looking at the handiwork of a race more advanced than my own. The idea that the moon had possessed intelligence at all was still almost too tremendous to grasp and my pride would not let me take the final emiliating plunge. Then I noticed something that sets the scope crawling at the back of my neck, something so trivial and so innocent that many would never have noticed it at all. I have said that the plateau was guard by meteors. It was also coated in inches deep with a cosmic dust that's always filtering down upon the surface of any world where there are no winds to disturb it. The dust and the meteors scratches ended quite abruptly in a wide circle in closing the little pyramid, as though an invisible wall was protecting it from the ravages of time

17:26and the slow but ceaseless bombardment from space. I was someone shouting in my earphones and I realized that Garnet had been calling me for quite a while. I walked unsteadily to the edge of the cliff and signaled him to join me, not trusting myself to speak. Then I went back toward that circle in the dust. I picked up a fragment of splintered rock and tossed it gently toward the shining enigma. If the public had vanished at that invisible barrier I should not have been surprised, but it seemed to hit a smooth hemispherical surface and slide gently to the ground. I knew then that I was looking at nothing that could be matched in the antiquity of my own race. This was not a building, but a machine, protecting itself with forces that had challenged eternity. Those forces, whatever they might be, were still operating and perhaps I'd already come too close.

18:26I thought of all the radiations man had trapped and tamed in the past century. For all I knew I might be as irrevocably doomed as if I had stepped into the deadliest silent aura of an unhielded nuclear pile. I remember turning then toward Garnet, who had joined me and was now standing motionless at my side. He seemed quite oblivious to me, so I did not disturb him but walked to the edge of the cliff in an effort to marshal my thoughts. There below me lay the merry chrysium sea of crises indeed, strange and weird to most men, but reassuringly familiar to me. I lifted my eyes toward the crescent earth, lying in her cradle of stars, and I wondered what her clouds had covered when these unknown builders had finished their work. Was it the steaming jungle of the Carboniferous, the bleak shoreline over which the first amphibians

19:28must crawl to conquer the land, or earlier still, the long loneliness before the coming of life? Do not ask me why I did not guess the truth sooner, the truth that seemed so obvious now. In the first excitement of my discovery, I had assumed without question that this crystalline apparition had been built by some race belonging to the Moon's remote past. But suddenly, and with overwhelming force, the belief came to me that it was as alien to the Moon as I myself. In twenty years we had found no trace of life but a few degenerate plants, no lunar civilization, whatever its doom could have laughed but a single token of its existence. I looked at the shining pyramid again, and the more remote it seemed from anything that

20:29had to do with the Moon. And suddenly I found 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 saying something like, 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 the savage might of nuclear 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 para-physical forces.

21:29The 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. Or 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

22:32long ago, other races on the world of other sons must have scaled and passed the heights that we have reached. Think of such civilizations far back in time against the fading after-gloved creation. Masters of universe so young that life as yet had come only to a handful of worlds. There's 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 people would 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 al-is beyond Prado.

23:33It 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 favor 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, a Sentinel watching over all worlds with a promise of life. There was a beacon that down the ages has been patiently signalling the fact that no one had discovered it. Perhaps you understand now why that crystal pyramid was set upon the moon instead of on

24:36the Earth. Its builders were not concerned with races still struggling up from savage rain. 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 lead sooner or later. It is a double challenge for the pens and turn upon the conquest of nuclear energy and the last choice between life and death. Once we have 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.

25:40I 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 assembly, 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.

26:49You have heard the Sentinel by Arthur C. Clarke, a story which first appeared in the Avon Science Fiction and Fantasy Reader, copyright 1951 by Avon. I'm Michael Hansen, technical production for this broadcast by Rich Grote. Mindwabs is produced at WHA Radio and Madison, a service of University of Wisconsin Extension.