The Sentinel

by Arthur C. Clarke

  Stormgren did his best to smile at the well-worn joke.

  “I think I’ve told everything,” he concluded. “As for the machine that takes me up to Karellen’s ship, the room in which I travel is as featureless as an elevator cage. Apart from the couch and table, it might very well be one.”

  There was silence for several minutes while the physicist embroidered his writing pad with meticulous and microscopic doodles. No one could have guessed that behind that still almost unfurrowed brow the world’s finest technical brain was working with the icy precision that had made it famous.

  Then Duval nodded to himself in satisfaction, leaned forward and pointed his pencil at Stormgren.

  “What makes you think, Rikki,” he asked, “that Karellen’s vision-screen, as you call it, really is what it pretends to be?”

  “I’ve always taken it for granted—it’s exactly like one. What else would it be, anyway?”

  “The tendency of otherwise first-class minds to overlook the obvious always saddens me. You know that Karellen can watch your movements, but a television system must have some sort of camera. Where is it?”

  “I’d thought of that,” said Stormgren with asperity. “Couldn’t the screen do both jobs? I know our televisors don’t, but still—”

  Duval didn’t like the idea.

  “It would be possible,” he admitted. “But why on earth go to all that trouble? The simplest solution is always best. Doesn’t it seem far more probable that your ‘vision-screen’ is really nothing more complicated than a sheet of one-way glass?”

  Stormgren was so annoyed with himself that for a moment he sat in silence, retracing the past. From the beginning, he had never challenged Karellen’s story—yet now he came to look back, when had the Supervisor ever told him that he was using a television system? He had just taken it for granted; the whole thing had been a piece of psychological trickery, and he had been completely deceived. He tried to console himself with the thought that in the same circumstances even Duval would have fallen into the trap.

  But he was jumping to conclusions: no one had proved anything yet.

  “If you’re right,” he said, “all I have to do is smash the glass—”

  Duval sighed.

  “These nontechnical laymen! Do you think it’s likely to be made of anything you could smash without explosives? And if you succeeded, do you imagine that Karellen is likely to breathe the same air as we do? Won’t it be nice for both of you if he flourishes in an atmosphere of chlorine?”

  Stormgren turned rather pale.

  “Well, what do you suggest?” he asked with some exasperation.

  “I want to think it over. First of all we’ve got to find if my theory is correct, and if so learn something about the material of the screen. I’ll put some of my best men on the job—by the way, I suppose you carry a briefcase when you visit the Supervisor? Is it the one you’ve got there?”

  “Yes.”

  “It’s rather small. Will you get one at least ten inches deep, and use it from now on so that he becomes used to seeing it?”

  “Very well,” said Stormgren doubtfully. “Do you want me to carry a concealed X-ray set?”

  The physicist grinned.

  “I don’t know yet, but we’ll think of something. I’ll let you know what it is in about a month’s time.”

  He gave a little laugh.

  “Do you know what all this reminds me of?”

  “Yes,” said Stormgren promptly, “the time you were building illegal radio sets during the German occupation.”

  Duval looked disappointed.

  “Well, I suppose I have mentioned that once or twice before. But there’s one other thing—”

  “Yes?”

  “When you’re caught, I didn’t know what you wanted the gear for.”

  “What, after all the fuss you once made about the scientist’s social responsibility for his inventions? Really, Pierre, I’m ashamed of you!”

  Stormgren laid down the thick folder of typescript with a sigh of relief.

  “Thank heavens that’s settled at last,” he said. “It’s strange to think that those few hundred pages hold the future of Europe.”

  “They hold a good deal more than that,” said Karellen quietly.

  “So a lot of people have been suggesting. The preamble, and most of the constitution itself, won’t need many alterations when it’s time for the rest of the world to join. But the first step will be quite enough to get on with.”

  Stormgren dropped the file into his briefcase, the back of which was now only six inches from the dark rectangle of the screen. From time to time his fingers played across the locks in a half-conscious nervous reaction, but he had no intention of pressing the concealed switch until the meeting was over. There was a chance that something might go wrong: though Duval had sworn that Karellen would detect nothing, one could never be sure.

  “Now, you said you’d some news for me,” Stormgren continued, with scarcely concealed eagerness. “Is it about—”

  “Yes,” said Karellen. “I received the Policy Board’s decision a few hours ago, and am authorized to make an important statement. I don’t think that the Freedom League will be very satisfied, but it should help to reduce the tension. We won’t record this, by the way.

  “You’ve often told me, Rikki, that no matter how unlike you we are physically, the human race will soon grow accustomed to us. That shows a lack of imagination on your part. It would probably be true in your case, but you must remember that most of the world is still uneducated by any reasonable standards, and is riddled with prejudices and superstitions that may take another hundred years to eradicate.

  “You will grant us that we know something of human psychology. We know rather accurately what would happen if we revealed ourselves to the world in its present state of development. I can’t go into details, even with you, so you must accept my analysis on trust. We can, however, make this definite promise, which should give you some satisfaction. In fifty years—two generations from now—we shall come down from our ships and humanity will at last see us as we are.”

  Stormgren was silent for a while. He felt little of the satisfaction that Karellen’s statement would have once given him. Indeed, he was somewhat confused by his partial success and for a moment his resolution faltered. The truth would come with the passage of time, and all his plotting was unnecessary and perhaps unwise. If he still went ahead, it would only be for the selfish reason that he would not be alive fifty years from now.

  Karellen must have seen his irresolution, for he continued:

  “I’m sorry if this disappoints you, but at least the political problems of the near future won’t be your responsibility. Perhaps you still think that our fears are unfounded, but believe me we’ve had convincing proof of the dangers of any other course.”

  Stormgren leaned forward, breathing heavily.

  “I always thought so! You have been seen by Man!”

  “I didn’t say that,” Karellen answered after a short pause. “Your world isn’t the only planet we’ve supervised.”

  Stormgren was not to be shaken off so easily.

  “There have been many legends suggesting that Earth has been visited in the past by other races.”

  “I know: I’ve read the Historical Research Section’s report. It makes Earth look like the crossroads of the Universe.”

  “There may have been visits about which you know nothing,” said Stormgren, still angling hopefully. “Though since you must have been observing us for thousands of years, I suppose that’s rather unlikely.”

  “I suppose it is,” said Karellen in his most unhelpful manner. And at that moment Stormgren made up his mind.

  “Karellen,” he said abruptly, “I’ll draft out the statement and send it up to you for approval. But I reserve the right to continue pestering you, and if I see any opportunity, I’ll do my best to learn your secret.”

  “I’m perfectly well aware of that,” replied the Supe
rvisor, with a slight chuckle.

  “And you don’t mind?”

  “Not in the slightest—though I draw the line at atomic bombs, poison gas, or anything else that might strain our friendship.”

  Stormgren wondered what, if anything, Karellen had guessed. Behind the Supervisor’s banter he had recognized the note of understanding, perhaps—who could tell?—even of encouragement.

  “I’m glad to know it,” Stormgren replied in as level a voice as he could manage. He rose to his feet, bringing down the cover of his case as he did so. His thumb slid along the catch.

  “I’ll draft that statement at once,” he repeated, “and send it up on the teletype later today.”

  While he was speaking, he pressed the button—and knew that all his fears had been groundless. Karellen’s senses were no finer than Man’s. The Supervisor could have detected nothing, for there was no change in his voice as he said goodbye and spoke the familiar code words that opened the door of the chamber.

  Yet Stormgren still felt like a shoplifter leaving a department store under the eyes of the house detective, and breathed a sigh of relief when the airlock doors had finally closed behind him.

  V

  “I admit,” said van Ryberg, “that some of my theories haven’t been very bright. But tell me what you think of this one.”

  “Must I?”

  Pieter didn’t seem to notice.

  “It isn’t really my idea,” he said modestly. “I got it from a story of Chesterton’s. Suppose that the Overlords are hiding the fact that they’ve got nothing to hide?”

  “That sounds a little complicated to me,” said Stormgren, beginning to take slight interest.

  “What I mean is this,” van Ryberg continued eagerly. “I think that physically they’re human beings like us. They realize that we’ll tolerate being ruled by creatures we imagine to be—well, alien and super-intelligent. But the human race being what it is, it just won’t be bossed around by creatures of the same species.”

  “Very ingenious, like all your theories,” said Stormgren. “I wish you’d give them Opus numbers so that I could keep up with them. The objections to this one—”

  But at that moment Alexander Wainwright was ushered in.

  Stormgren wondered what he was thinking. He wondered, too, if Wainwright had made any contact with the men who had kidnapped him. He doubted it, for he believed Wainwright’s disapproval of violent methods to be perfectly genuine. The extremists in his movement had discredited themselves thoroughly, and it would be a long time before the world heard of them again.

  The head of the Freedom League listened in silence while the draft was read to him. Stormgren hoped that he appreciated this gesture, which had been Karellen’s idea. Not for another twelve hours would the rest of the world know of the promise that had been made to its grandchildren.

  “Fifty years,” said Wainwright thoughtfully. “That is a long time to wait.”

  “Not for Karellen, nor for humanity,” Stormgren answered. Only now was he beginning to realize the neatness of the Overlords’ solution. It had given them the breathing space they believed they needed, and it had cut the ground from beneath the Freedom League’s feet. He did not imagine that the League would capitulate, but its position would be seriously weakened.

  Certainly Wainwright realized this as well, as he must also have realized that Karellen would be watching him. For he said very little and left as quickly as he could: Stormgren knew that he would not see him again in his term of office. The Freedom League might still be a nuisance, but that was a problem for his successor.

  There were some things that only time could cure. Evil men could be destroyed, but nothing could be done about good men who were deluded.

  “Here’s your case,” said Duval. “It’s as good as new.”

  “Thanks,” Stormgren answered, inspecting it carefully nonetheless. “Now perhaps you can tell me what it was all about—and what we are going to do next.”

  The physicist seemed more interested in his own thoughts.

  “What I can’t understand,” he said, “is the ease with which we’ve got away with it. Now if I’d been Kar—”

  “But you’re not. Get to the point, man. What did we discover?”

  “Ah me, these excitable, highly strung Nordic races!” sighed Duval. “Well, it’s rather a long story, but the first piece of equipment you carried was a tiny echo sounder using supersonic waves. We went right up the audio spectrum, so high that I was sure no possible sense organs could detect us. When you pressed the button, a rather complicated set of sound pulses went out in various directions. I won’t bother about the details, but the main idea was to measure the thickness of the screen and to find the dimensions of the room, if any, behind it.

  “The screen seems to be about five inches thick, and the space behind it is at least ten yards across. We couldn’t detect any echo from the further wall, but we hardly expected to. However, we did get this.”

  He pushed forward a photographic record which to Stormgren looked rather like the autograph of a mild earthquake.

  “See that little kink?”

  “Yes: what is it?”

  “Only Karellen.”

  “Good Lord! Are you sure?”

  “It’s a pretty safe guess. He’s sitting, or standing, or whatever he does, about two yards on the other side of the screen. If the resolution had been better, we might even have calculated his size.”

  Stormgren’s feelings were very mixed as he stared at the scarcely visible deflection of the trace. Until now, there had been no proof that Karellen even had a material body. The evidence was still indirect, but he accepted it with little question.

  Duval’s voice cut into his reverie.

  “The piece of equipment you carried on your second visit was similar,” he said, “but used light instead of sound. We had to measure the transmission characteristics of the screen, and that presented considerable difficulties. Obviously we dared not use visible light, so once again we chose frequencies so high that we couldn’t imagine any eye focusing them—or any atmosphere transmitting them very far. And again we managed to carry it off.

  “You’ll realize,” he continued, “that there’s no such thing as a truly one-way glass. Karellen’s screen, we found when we analyzed our results, transmits about a hundred times as easily in one direction as the other. We’ve no particular reason to assume that the figure is very different in the visible spectrum—but we’re giving you an enormous safety margin.”

  With the air of a conjuror producing a whole litter of rabbits, Duval reached into his desk and pulled out a pistol-like object with a flexible bell mouth. It reminded Stormgren of a rubber blunderbuss, and he couldn’t imagine what it was supposed to be.

  Duval grinned at his perplexity.

  “It isn’t as dangerous as it looks. All you have to do is to ram the muzzle against the screen and press the trigger. It gives out a very powerful flash lasting five seconds, and in that time you’ll be able to swing it round the room. Enough light will come back to give you a good view.”

  “It won’t hurt Karellen?”

  “Not if you aim low and sweep it upwards. That will give him time to accommodate—I suppose he has reflexes like ours, and we don’t want to blind him.”

  Stormgren looked at the weapon doubtfully and hefted it in his hand. For the last few weeks his conscience had been pricking him. Karellen had always treated him with unmistakable affection, despite his occasional devastating frankness, and now that their time together was drawing to its close he did not wish to do anything that might spoil that relationship. But the Supervisor had received due warning, and Stormgren had the conviction that if the choice had been his Karellen would long ago have shown himself. Now the decision would be made for him: when their last meeting came to its end, Stormgren would gaze upon Karellen’s face.

  If, of course, Karellen had a face.

  The nervousness that Stormgren had first felt had long since passed
away. Karellen was doing almost all the talking, weaving the long, intricate sentences of which he was so fond. Once this had seemed to Stormgren the most wonderful and certainly the most unexpected of all Karellen’s gifts. Now it no longer appeared quite so marvelous, for he knew that like most of the Supervisor’s abilities it was the result of sheer intellectual power and not of any special talent.

  Karellen had time for any amount of literary composition when he slowed his thoughts down to the pace of human speech.

  “Do not worry,” he said, “about the Freedom League. It has been very quiet for the past month, and though it will revive again it is no longer a real danger. Indeed, since it’s always valuable to know what your opponents are doing, the League is a very useful institution. Should it ever get into financial difficulties I might even subsidize it.”

  Stormgren had often found it difficult to tell when Karellen was joking. He kept his face impassive and continued to listen.

  “Very soon the League will lose another of its strongest arguments. There’s been a good deal of criticism, mostly rather childish, of the special position you have held for the past few years. I found it very valuable in the early days of my administration, but now that the world is moving along the line that I planned, it can cease. In the future, all my dealings with Earth will be indirect and the office of Secretary-General can once again become what it was originally intended to be.

  “During the next fifty years there will be many crises, but they will pass. Almost a generation from now, I shall reach the nadir of my popularity, for plans must be put into operation which cannot be fully explained at the time. Attempts may even be made to destroy me. But the pattern of the future is clear enough, and one day all these difficulties will be forgotten—even to a race with memories as long as yours.”

  The last words were spoken with such a peculiar emphasis that Stormgren immediately froze in his seat. Karellen never made accidental slips and even his indiscretions were calculated to many decimal places. But there was no time to ask questions—which certainly would not be answered—before the Supervisor had changed the subject again.