Masquerade
Clifford D. Simak
Copyright 1941

   Old Creepy was down in the control room, sawing lustily on his screeching fiddle.
   On the sun-blasted plains outside the Mercutian Power Centre, the Roman Candles, snatching their shapes from Creepy's mind, had assumed the form of Terrestrial hill-billies and were cavorting through the measure of a square dance.
   In the kitchen, Rastus rolled two cubes about the table, crooning to them, feeling lonesome because no one would shoot a game of craps with him.
   Inside the refrigeration room, Mathilde, the cat, stared angrily at the slabs of frozen beef above her head, felt the cold of the place and meowed softly, cursing herself for never being able to resist the temptation of sneaking in when Rastus wasn't looking.
   Up in the office, at the peak of the great photocell that was the centre, Curt Craig stared angrily across the desk at Norman Page.
   One hundred miles away, Knut Anderson, encased in a cumbersome photocell spacesuit, stared incredulously at what he saw inside the space warp.
   The communications bank snarled warningly and Craig swung about in his chair, lifted the handset off the cradle and snapped recognition into the mouthpiece.
   "This is Knut, chief," said a voice, badly blurred by radiations.
   "Yes," yelled Craig. "What did you find?"
   "A big one," said Knut's voice.
   "Where?"
   "I'll give you the location."
   Craig snatched up a pencil, wrote rapidly as the voice spat and crackled at him.
   "Bigger than anything on record," shrilled Knut's voice. "Space busted wide open and twisted all to hell. The instruments went nuts."
   "We'll have to slap a tracer on it," said Craig, tensely. "Take a lot of power, but we've got to do it. If that thing starts to move —"
   Knut's voice snapped and blurred and sputtered so Craig couldn't hear a word he said.
   "You come back right away," Craig yelled. "It's dangerous out there. Get too close to that thing. Let it swing toward you and you —"
   Knut interrupted, his voice wallowing in the wail of tortured beam. "There's something else, chief. Somthing funny. Damn funny —"
   The voice pinched out.
   Craig shrieked into the mouthpiece. "What is it, Knut? What's funny?"
   He stopped, astonished, for suddenly the crackle and hissing and whistle of the communications beam was gone'.
   His left hand flicked out to the board and snapped a toggle. The board hummed as tremendous power surged into the call. It took power - lots of power, to maintain a tight beam on Mercury. But there was no answering hum - no indication the beam was being restored.
   Something had happened out there! Something had snapped the beam.
   Craig stood up, white-faced, to stare through the ray filter port to the ashy plains. Nothing to get excited about. Not yet, anyway. Wait for Knut to get back. It wouldn't take long. He had told Knut to start at once, and those puddle jumpers could travel.
   But what if Knut didn't come back? What if that space warp had moved?
   The biggest one on record, Knut had said. Of course, there always were a lot of them one had to keep an eye on, but very few big enough to really worry about. Little whirlpools and eddies where the spacetime continuum was wavering around, wondering which way it ought to jump.
   Not dangerous, just a bother. Had to be careful not to drive a puddle jumper into one. But a big one, if it started to move, might engulf the plant . . .
   Outside, the Candles were kicking up the dust, shuffling and hopping and flapping their arms. For the moment they were mountain folk back in the hills of Earth, having them a hoe down. But there was something grotesque about them - like scarecrows set to music.
   The plains of Mercury stretched away to the near horizon, rolling plains of bitter dust. The Sun was a monstrous thing of bright-blue flame in a sky of inky black, ribbons of scarlet curling out like snaky tentacles.
   Mercury was its nearest to the Sun a mere 29,000,000 miles distant, and that probably explained the warp. The nearness to the Sun and the epidemic of sunspots. Although the sunspots may not have had anything to do with it. Nobody knew.
   Craig had forgotten Page until the man coughed, and then he turned to the desk.
   "I hope," said Page, "that you have reconsidered. This project of mine means a lot to me."
   Craig was suddenly swept with anger at the man's persistence.
   "I gave you my answer once," he snapped. "That is enough. When I say a thing, I mean it."
   "I can't see your objection," said Page flatly. "After all, these Candles -"
   "You're not capturing any Candles," said Craig. "Your idea is the most crackpot, from more than one viewpoint, that I have ever heard."
   "I can't understand this strange attitude of yours," argued Page. "I was assured at Washington —"
   Craig's anger flared. "I don't give a damn what Washington assured you. You're going back as soon as the oxygen ship comes in. And you're going back without a Candle."
   "It would do no harm. And I'm prepared to pay well for any services you —"
   Craig ignored the hinted bribe, levelled a pencil at Page.
   "Let me explain it to you once again." he said. "Very carefully and in full, so you will understand.
   "The Candles are natives of Mercury. They were here first. They were here when men came, and they'll probably be here long after men depart. They have let us be and we have let them be. And we have let them be for just one reason - one damn good reason. You see, we don't know what they could do if we stirred them up. We are afraid of what they might do."
   Page opened his mouth to speak, but Craig waved him into silence and went on.
   "They are organisms of pure energy. Things that draw their life substance directly from the Sun -just as you and I do. Only we get ours by a roundabout way. Lot more efficient than we are by that very token, for they absorb their energy direct, while we get ours by chemical processes.
   "And when we've said that much - that's about all we can say. Because that's all we know about them. We've watched those Candles for five hundred years and they still are strangers to us."
   "You think they are intelligent?" asked Page, and the question was a sneer.
   "Why not?" snarled Craig. "You think they aren't because Man can't communicate with them. Just because they didn't break their necks to talk with men.
   "Just because they haven't talked doesn't mean they aren't intelligent. Perhaps they haven't communicated with us because their thought and reasoning would have no common basis for intelligent communication with mankind. Perhaps it's because they regard Man as an inferior race - a race upon which it isn't even worth their while to waste their time."
   "You're crazy," yelled Page. "They have watched us all these years. They've seen what we can do. They've seen our space ships - they've seen us build this plant - they've seen us shoot power across millions of miles to the other planet."
   "Sure," agreed Craig, "they've seen all that. But would it impress them? Are you sure it would? Man, the great architect! Would you bust a gut trying to talk to a spider, or an orchard oriole, or a mud wasp? You bet your sweet life you wouldn't. And they're great architects, every one of them."
   Page bounced angrily in his chair. "If they're superior to us," he roared, "where are the things they've done? Where are their cities, their machines, their civilisations?"
   "Perhaps," suggested Craig, "they outlived machines and cities millennia ago. Perhaps they've reached a stage of civilisation where they don't need mechanical things." He tapped the pencil on the desk.
   "Consider this. Those Candles are immortal. They'd have to be. There'd be nothing to kill them. They apparently have no bodies - just balls of energy. That's their answer to their environment. And you have the nerve to think of capturing some of them! You, who know nothing about them, plan to take them back to Earth to use as a circus attraction, a side-show drawing card - something for fools to gape at!"
   "People come out here to see them," Page countered. "Plenty of them. The tourist bureau use them in their advertising."
   "That's different," roared Craig. "If the Candles want to put on a show on home territory, there's nothing we can do about it. But you can't drag them away from here and show them off. That would spell trouble and plenty of it!"
   "But if they're so damned intelligent?" yelped Page, "why do they put on those shows at all? Just think of something and presto! - they're it. Greatest mimics in the Solar System. And they never get anything right. It's always cock-eyed. That's the beauty of it."
   "It's cock-eyed," snapped Craig, "because man's brain never fashions a letter-perfect image. The Candles pattern themselves directly after the thoughts they pick up. When you think of something you don't give them all the details - your thoughts are sketchy. You can't blame the Candles for that. They pick up what you give them and fill in the rest as best they can. Therefore camels with flowing manes, camels with four and five humps, camels with horns, an endless parade of screwball camels, if camels are what you are thinking of."
   He flung the pencil down angrily.
   "And don't you kid yourself the Candles are doing it to amuse us. More than likely they believe we are thinking up all these swell ideas just to please them. They're having the time of their lives. Probably that's the only reason they've tolerated us here - because we have such amusing thoughts.
   "When Man first came here they were pretty, coloured balls rolling around on the surface, and someone called them Roman Candles because that's what they looked like. But since that day ' they've been everything Man has ever thought of."
   Page heaved himself out of the chair.
   "I shall report your attitude to Washington, Captain Craig."
   "Report and be damned," growled Craig. "Maybe you've forgotten where you are. You aren't back on Earth, where bribes and boot-licking and bulldozing will get a man almost anything he wants. You're at the power centre on the Sunward side of Mercury. This is the main source of power for all the planets. Let this power plant fail, let the transmission beams be cut off and the Solar System goes to hell!"
   He pounded the desk for emphasis.
   "I'm in charge here, and when I say a thing it stands for you as well as anyone. My job is to keep this plant going, keep the power pouring out to the planets. And I'm not letting some half-baked fool come out here and make me trouble. While I'm here, no one is going to stir up the Candles. We've got plenty of trouble without that."
   Page edged toward the door, but Craig stopped him.
   "Just a little word of warning," he said, speaking softly. "If I were you, I wouldn't try to sneak out any of the puddle jumpers, including your own. After each trip the oxygen tank is taken out and put into the charger, so it'll be at first capacity for the next trip. The charger is locked and there's just one key. And I have that."
   He locked eyes with the man at the door and went on.
   "There's a little oxygen left in the jumper, of course. Half an hour's supply, maybe. Possibly less. After that there isn't any more. It's not nice to be caught like that. They found a fellow who that had happened to just a day or so ago over near one of the Twilight Belt stations."
   But Page was gone, slamming the door.
   The Candles had stopped dancing and were rolling around, drifting bubbles of every hue. Occasionally one would essay the formation of some object, but the attempt would be half-hearted and the Candle once more would revert to its natural sphere.
   Old Creepy must have put his fiddle away, Craig thought. Probably he was making an inspection round, seeing if everything was all right. Although there was little chance that anything could go wrong. The plant was automatic, designed to run with the minimum of human attention.
   The control room was a wonder of clicking, chuckling, chortling, snicking gadgets. Gadgets that kept the flow of power directed to the substations on the Twilight Belt. Gadgets that kept the tight beams from the substations centred exactly on those points in space where each must go to be picked up by the substations circling the outer planets.
   Let one of those gadgets fail - let that spaceward beam sway as much as a fraction of a degree . . . Curt shuddered at the thought of a beam of terrific power smashing into a planet -perhaps into a city. But the mechanism had never failed - never would. It was foolproof. A far cry from the day when the plant had charged monstrous banks of converters to be carted to the outer worlds by lumbering spaceships.
   This was really free power, easy power, plentiful power. Power carried across millions of miles on Addison's tight-beam principle. Free power to develop the farms of Venus, the mines of Mars, the chemical plants and cold laboratories on Pluto.
   Down there in the control room, too, were other gadgets as equally important. The atmosphere machine, for example, which kept the air mixture right, drawing on those tanks of liquid oxygen and nitrogen and other gases brought across space from Venus by the monthly oxygen ship. The refrigerating plant, the gravity machine, the water assembly.
   Craig heard the crunch of Creepy's footsteps on the stairs and turned to the door as the old man shuffled into the room.
   Creepy's brows were drawn down and his face looked like a thunder-cloud.
   "What's the matter now?" asked Craig.
   "By cracky," snapped Creepy, "you got to do something about that Rastus."
   Craig grinned. "What's up this time?"
   "He stole my last bottle of drinking liquor," wailed Creepy. "I was hoarding if for medical purposes, and now it's gone. He's the only one who could have taken it."
   "I'll talk to Rastus," Craig promised.
   "Some day," threatened Creepy, "I'm going to get my dander up and whale the everlastin' tar out of that smoke. That's the fifth bottle of liquor he's swiped off me."
   The old man shook his head dolefully, whuffled his walrus-like moustache.
   "Aside from Rastus, how's everything else going?" asked Craig.
   "Earth just rounded the Sun," the old man said. "The Venus station took up the load."
   Craig nodded. That was routine. When one planet was cut off by the Sun, the substations of the nearest planet took on an extra load, diverted part of it to the first planet's stations, carrying it until it was clear again.
   He arose from the chair and walked to the port, stared out across the dusty plains. A dot was moving across the near horizon. A speedy dot, seeming to leap across the dead, grey wastes.
   "Knut's coming!" he yelled to Creepy.
   Creepy hobbled for the doorway. "I'll go down to meet him.
   Knut and me are having a game of checkers as soon as he gets in."
   Craig laughed, relieved by Knut's appearance. "How many checker games have you and Knut played?" he asked.
   "Hundreds of 'em," Creepy declared proudly. "He ain't no match for me, but he thinks he is. I let him beat me regular to keep the interest up. I'm afraid he'd quit playing if I beat him as often as I could."
   He started for the door and then turned back. "But this is my turn to win." The old man chuckled in his moustache.."I'm goin' to give him a first-class whippin'."
   "First," said Craig, "tell him I want to see him."
   "Sure," said Creepy, "and don't you go telling him about me letting him beat me. That would make him sore."
   Craig tried to sleep but couldn't. He was worried. Nothing definite, for there seemed no cause to worry. The tracer placed on the big warp revealed that it was moving slowly, a few feet an hour or so, in a direction away from the centre. No other large ones had shown up in the directors. Everything, for the moment, seemed under control. Just little things. Vague suspicions and wondering - snatches here and there that failed to fall into the pattern.
   Knut, for instance. There wasn't anything wrong with Knut, of course, but while he had talked to him he had sensed something. An uneasy feeling that Ijfted the hair on the nape of his neck, made the skin prickle along his spine. Yet nothing one could lay one's hands on.
   Page, too. The damn fool probably would try to sneak out and capture some Candles and then there'd be all hell to pay.
   Funny, too, how Knut's radios, both in his suit and in the jumper, had gone dead. Blasted out, as if they had been raked by a surge of energy. Knut couldn't explain it, wouldn't try. Just shrugged his shoulders. Funny things always were happening on Mercury.
   Craig gave up trying to sleep, slid his feet into slippers and walked across the room to the port. With a flip of his hand he raised the shutter and stared out.
   Candles were rolling around. Suddenly one of them materialised into a monstrous whisky bottle, lifted in the air, tilted, liquid pouring to the ground.
   Craig chuckled. That would be either Old Creepy bemoaning the loss of that last bottle or Rastus sneaking off to where he'd hid it to take another nip.
   A furtive tap came on the door, and Craig wheeled. For a tense moment he crouched, listening, as if expecting an attack. Then he laughed softly to himself. He was jumpy, and no fooling. Maybe what he needed was a drink.
   Again the tap, more insistent, but still furtive.
   "Come in," Craig called.
   Old Creepy sidled into the room. "I hoped you wasn't asleep," he said.
   "What is it, Creepy?" And even as he spoke, Craig felt himself going tense again. Nerves all shot to hell.
   Creepy hitched forward.
   "Knut," he whispered. "Knut beat me at checkers. Six times hand running! I didn't have a chance!"
   Craig's laugh exploded in the room.
   "But I could always beat him before," the old man insisted. "I even let him beat me every so often to keep him interested so he would play with me. And tonight I was all set to take him to a cleaning —"
   Creepy's face twisted, his moustache quivering.
   "And that ain't all, by cracky. I felt, somehow, that Knut had changed and —"
   Craig walked close to the old man, grasped him by the shoulder. "I know," he said. "I know just how you felt." Again he was remembering how the hair had crawled upon his skull as he talked to Knut just a while ago.
   Creepy nodded, pale eyes blinking, Adam's apple bobbing.
   Craig spun on his heel, snatched up his shirt, started peeling off his pyjama coat.
   "Creepy," he rasped, "you go down to that control room. Get a gun and lock yourself in. Stay there until I get back. And don't let anyone come in!"
   He fixed the old man with a stare. "You understand. Don't let anyone get in! Use your gun if you are forced to use it. But see no one touches those controls!"
   Creepy's eyes bulged and he gulped. "Is there going to be trouble?" he quavered.
   "I don't know," snapped Craig, "but I'm going to find out."
   Down in the garage, Craig stared angrily at the empty stall.
   Page's jumper was gone!
   Grumbling with rage, Craig walked to the oxygen-tank rack. The lock was undamaged, and he inserted the key. The top snapped up and revealed the tanks - all of them, nestling in rows, still attached to the recharger lines. Almost unbelieving, Craig stood there, looking at the tanks.
   All of them were there. That meant Page had started out in the jumper with insufficient oxygen. It meant the man would die out on the blistering wastes of Mercury. That he might go mad and leave his jumper and wander into the desert, a raving maniac, like the man they'd found out near the Twilight station.
   Craig swung about, away from the tanks, and then stopped, thoughts spinning in his brain. There wasn't any use of hunting Page. The damn fool probably was dead by now. Sheer suicide, that was what it was. Sheer lunacy. And he had warned him, too!
   And he, Craig, had work to do. Something had happened out there at the space warp. He had to lay those tantalising suspicions that rummaged through his mind. There were some things he had to be sure about. He didn't have time to go hunting a man who was already dead, a damn fool who had committed suicide. The man was nuts to start with. Anyone who thought he could capture Candles . . .
   Savagely, Craig closed one of the line valves, screwed shut the tank valve, disconnected the coupling and lifted the tank out of the rack. The tank was heavy. It had to be heavy to stand a pressure of 200 atmospheres.
   As he started for the jumper, Mathilde, the cat, strolled down the ramp from the floor above and walked between his legs. Craig stumbled and almost fell, recovered his balance with a mighty effort and cursed Mathilde with a fluency born of practice.
   "Me-ow-ow-ow," said Mathilde conversationally.
   There is something unreal about the Sunward side of Mercury, an abnormality that is sensed rather than seen.
   There the Sun is nine times larger than seen from Earth, and the thermometer never registers under 650 degrees Fahrenheit. Under that terrific heat, accompanied by blasting radiations hurled out by the Sun, men must wear photocell spacesuits, must ride photocell cars and live in the power centre which in itself is little more than a mighty photocell. For electric power can be disposed of, while heat and radiation often cannot be.
   There the rock and soil have been crumbled into dust under the lashing of heat and radiations. There the horizon is near, always looming just ahead, like an ever-present brink.
   But it is not these things that make the planet so alien. Rather, it is the strange distortion of lines, a distortion that one sometimes thinks he can see, but is never sure. Perhaps the very root of that alien sense is the fact that the Sun's mass makes a straight line an impossibility, a stress that bends magnetic fields and stirs up the very structure of space itself.
   Curt Craig felt that strangeness of Mercury as he zoomed across the dusty plain. The puddle jumper splashed through a small molten pool, spraying it out in sizzling sheets. A pool of lead, or maybe tin.
   But Craig scarcely noticed. At the back of his brain pounded a thousand half-formed questions. His eyes, edged by crow's-feet, squinted through the filter shield, following the trail left by Knut's returning machine. The oxygen tank hissed softly and the atmosphere mixer chuckled. But all else was quiet.
   A howl of terror and dismay shattered the quiet. Craig jerked the jumper to a stop, leaped from his seat, hand streaking to his gun.
   Crawling from under the metal bunk bolted at the rear of the car was Rastus, the whites of his eyes showing like bull's-eyes.
   "Good Lawd," he bellowed, "Where is I?"
   "You're in a jumper, sixty miles from the Centre," snapped Craig. "What I want to know is how the hell you got here."
   Rastus gulped and rose to his knees. "You see, it was like this, boss," he stammered. "I was lookin' for Mathilde. Dat cat, she run me wild. She sneaks into the refrigerator all the time. I jus' can't trust her no place. So when she turned up missin' —"
   He struggled to his feet, and as he did so a bottle slipped from his pocket, smashed to bits on the metal floor. Pale-amber liquor ran among the fragments.
   Craig eyed the shattered glass. "So you were hunting Mathilde, eh?"
   Rastus slumped on the bunk, put his head in hs hands. "Ain't no use lyin' to you, boss," he acknowledged. "Never gets away with it. I was havin' me a drink. Just a little nip. And I fell asleep."
   "You hid the bottle you swiped from Creepy in the jumper," declared Craig flatly, "and you drank yourself to sleep."
   "Can't seem to help it," Rastus moaned. "'Ol' debbil's got me. Can't keep my hands off of a bottle, somehow. Ol' Mercury, he done dat to me. Ol' debbil planet. Nothin' as it should be. Ol' Man Sun pullin' the innards out of space. Playin' around with things until they ain't the same —"
   Craig nodded, almost sympathetically. That was the hell of it. Nothing ever was the same on Mercury. Because of the Sun's tremendous mass, light was bent, space was warped and eternally threatening to shift, basic laws required modification. The power of two magnets would not always be the same, the attraction between two electrical charges would be changed. And the worst of it was that a modification which stood one minute would not stand the next.
   "Where are we goin' now, boss?"
   "We're going out to the space warp that Knut found," said
   Craig. "And don't think for a minute I'll turn around and take you back. You got yourself into this, remember."
   Rastus's eyes batted rapidly and his tongue ran around his lips. "You said the warp, boss? Did I hear you right? The warp?"
   Craig didn't answer. He swung back to his seat, started the jumper once again.
   Rastus was staring out of one of the side ports. "There's a Candle followin' us," he announced. "Big blue feller. Skippin' along right with us all the time."
   "Nothing funny in that," said Craig. "They often follow us. Whole herds of them."
   "Only one this time," said Rastus. "Big blue feller."
   Craig glanced at the notation of the space warp's location. Only a few miles distant. He was almost there.
   There was nothing to indicate what the warp might be, although the instruments picked it up and charted it as he drew near. Perhaps if a man stood at just the right angle he might detect a certain shimmer, a certain strangeness, as if he were looking into a wavy mirror. But otherwise there probably would be nothing pointing to its presence. Hard to know just where one stopped or started. Hard to keep from walking into one, even with instruments.
   Curt shivered as he thought of the spacemen who had walked into just such warps in the early days. Daring mariners of space who had ventured to land their ships on the Sunward side, had dared to take short excursions in their old-type spacesuit. Most of them had died, blasted by the radiations spewed out by the Sun, literally cooked to death. Others had walked across the plain and disappeared. They had walked into the warps and disappeared as if they had melted into thin air. Although, of course, there wasn't any air to melt into - hadn't been for many million years.
   On this world, all free elements long ago had disappeared. Those elements that remained, except possibly far underground, were locked so stubbornly in combination that it was impossible to blast them free in any appreciable quantity. That was why liquid air was carted clear from Venus.
   The tracks in the dust and rubble made by Knut's machine were plainly visible, and Craig followed them. The jumper topped a slight rise and dipped into a slight depression. And in the centre of the depression was a queer shifting of light and dark, as if one were looking into a tricky mirror.
   That was the space warp!
   Craig glanced at the instruments and caught his breath. Here was a space warp that was really big. Still following the tracks of Knut's machine, he crept down into the hollow, swinging closer and closer to that shifting, almost invisible blotch that marked the warp.
   "Golly!" gasped Rastus, and Craig knew the Negro was beside him, for he felt his breath upon his neck.
   Here Knut's machine had stopped, and here Knut had gotten out to carry the instruments nearer, the blotchy tracks of his spacesuit like furrows through the powdered soil. And there he had come back. And stopped and gone forward again. And there . ..
   Craig jerked the jumper to a halt, stared in amazement and horror through the filter shield. Then, the breath sobbing in his throat, he leaped from the seat, scrambled frantically for a spacesuit.
   Outside the car, he approached the dark shape huddled on the ground. Slowly he moved nearer, the hands of fear clutching at his heart. Beside the shape he stopped and looked down. Heat and radiation had gotten in their work, shrivelling, blasting, desiccating - but there could be no doubt.
   Staring up at him from where it lay was the dead face of Knut Anderson!
   Craig straightened up and looked around. Candles danced upon the ridges, swirling and jostling, silent watchers of his grim discovery. The one lone blue Candle, bigger than the rest, had followed the machine into the hollow, was only a few rods away, rolling restlessly to and fro.
   Knut had said something was funny - had shouted it, his voice raspy and battered by the screaming of powerful radiations. Or had that been Knut? Had Knut already died when that message came through?
   Craig glanced back at the sand, the blood pounding in his temples. Had the Candles been responsible for this? And if they were, why was he unmolested, with hundreds dancing on the ridge?
   And if this was Knut, with dead eyes staring at the black of space, who was the other one - the one who came back?
   Candles masquerading as human beings? Was that possible? Mimics the Candles were - but hardly as good as that. There was always something wrong with their mimicry - something ludicrously wrong.
   He remembered now the look in the eyes of the returned Knut - that chilly, deadly look - the kind of look one sometimes sees in the eyes of ruthless men. A look that had sent cold chills chasing up his spine.
   And Knut, who was no match for Creepy at checkers, but who thought he was because Creepy let him win at regular intervals, had taken six games straight.
   Craig looked back at the jumper again, saw the frightened face of Rastus pressed against the filter shield. The Candles still danced upon the hills, but the big blue one was gone.
   Some subtle warning, a nasty little feeling between his shoulder blades, made Craig spin around to face the warp. Just in front of the warp stood a man, and for a moment Craig stared at him, frozen, speechless, unable to move.
    For the man who stood in front of him, not more than 40ft away, was Curt Craig!
   Feature for feature, line for line, that man was himself. A second Curt Craig. As if he had rounded a corner and met himself coming back.
   Bewilderment roared through Craig's brain, a baffling bewilderment. He took a quick step forward, then stopped. For the bewilderment suddenly was edged with fear, a knifelike sense of danger.
   The man raised a hand and beckoned, but Craig stayed rooted where he stood, tried to reason with his muddled brain. It wasn't a reflection, for if it had been a reflection it would have shown him in a spacesuit, and this man stood without a spacesuit. And if it were a real man, it wouldn't be standing there exposed to the madness of the Sun. Such a thing would have spelled sure and sudden death.
   Forty feet away - and yet within that 40ft, perhaps very close, the power of the warp might reach out, might entangle any man who crossed that unseen deadline. The warp was moving, at a few feet an hour, and this spot where he now stood, with Knut's dead body at his feet, had a few short hours ago been within the limit of the warp's influence.
   The man stepped forward, and as he did, Craig stepped back, his hands dropping to the gun butts. But with the guns half out he stopped, for the man had disappeared. Had simply vanished. There had been no puff of smoke, no preliminary shimmering as of matter breaking down. The man just simply wasn't there. But in his place was the big blue Candle, rocking to and fro.
   Cold sweat broke out upon Craig's forehead and trickled down his face. For he knew he had trodden very close to death - perhaps to something even worse than death. Wildly he swung about, raced for the puddle jumper, wrenched the door open, hurled himself at the controls.
   Rastus wailed at him. "What's the matter, boss?"
   "We have to get back to the centre," yelled Craig. "Old Creepy is back there all alone! Lord knows what has happened to him -what will happen to him."
   "But, boss," yipped Rastus, "what's the matter. Who was back there on the ground?"
   "That was Knut," said Craig.
   "But Mr Knut is back there at the centre, boss. I know. I seen him with my own eyes."
   "Knut isn't at the centre," Craig snapped. "Knut is dead out there by the warp. The thing that's at the centre is a Candle, masquerading as Knut!"
   Craig drove like a madman, the cold claws of fear hovering over him. Twice he almost met disaster, once when the jumper bucked through a deep drift of dust, again when it rocketed through a pool of molten tin.
   "But them Candles can't do that nohow," argued Rastus. "They can't get nothing right. Every time they try to be a thing they always get it wrong."
   "How do you know that?" snapped Craig. "How do you know they couldn't if they tried? And if they could and wanted to use it against us, do you think they would let us see them do it? Through all these years they have done their best to make us lower our guard. They have tried to make us believe they were nothing but a gang of good-natured clowns. That, my boy, is super-plus psychology."
   "But why?" demanded Rastus. "Why would they want to do it? We ain't never hurt them."
   "Ask me another one," said Craig grimly. "The best answer is that we don't know them. They might have a dozen reasons - reasons we couldn't understand. Reasons no human being could understand because they wouldn't tally with the things we know."
   Craig gripped the wheel hard and slammed the jumper up an incline slippery with dust.
   Damn it, the thing that had come back as Knut was Knut. It knew the things Knut knew, it acted like Knut. It had his mannerisms, it talked in his voice, it actually seemed to think the way Knut would think.
   What could a man - what could mankind do against a thing like that? How could it separate the original from the duplicate? How would it know its own?
   The thing that had come back to the Centre had beaten Creepy at checkers. Creepy had led Knut to believe he was the old man's equal at the game, although Creepy knew he could beat Knut at any time he chose. But Knut didn't know that - and the thing masquerading as Knut didn't know it. So it had sat down and beaten Creepy six games hand-running, to the old man's horror and dismay.
   Did that mean anything or not?
   Craig groaned and tried to get another ounce of speed out of the jumper.
   "It was that old blue jigger," said Rastus. "He was sashaying all around, and then he disappeared."
   Craig nodded. "He was in the warp. Apparently the Candles are able to alter their electronic structures so they may exist within the warp. They lured Knut into the warp by posing as human beings, arousing his curiosity, and when he stepped into its influence it opened the way for their attack. They can't get at us inside a suit, you see, because a suit is a photocell, and they are energy, and in a game of that sort, the cell wins every time.
   "That's what they tried to do with me. Lord knows what the warp would have done if I'd stepped into it, but undoubtedly it would have made me vulnerable in the fourth dimension or in some other way. That would have been all they needed."
   Rastus's eyes strayed to the litter of glass on the floor by the bunk. "Sho' wish I had me a snort of red-eye," he mourned. "Sho' could do with a little stimulus."
   "It was clever of them," Craig said. "A Trojan horse method of attack. First they got Knut, and next they tried to get me, and with two of them in the Centre it would not have been so hard to have gotten you and Creepy."
   He slapped the wheel a vicious stroke, venting his anger.
   "And the beauty of it was that no one would have known. The oxygen ship could have come from Venus and the men on board would never have been the wiser, for they would have met things that seemed like all four of us. No one would have guessed. They would have had time - plenty of time - to do anything they planned."
   "What you figure they was aimin' to do, boss?" queried Rastus. "Figure maybe they meant to blow up that ol' plant?"
   "I don't know, Rastus. How could I know? If they were human beings, I could make a guess, because I could put myself in their shoes and try to think the way they did. But with the Candles you can't do that. You can't do anything with the Candles, because you don't know what they are."
   "You aimin' to raise hell with dem Candles, boss?"
   "With what?" snapped Craig.
   "Just give me a razor," exulted Rastus. "Maybe two razors, one for each han'. I'se.a powerful dangerous man with a razor blade."
   "It'll take more than razors," said Craig. "More than our energy guns, for those things are energy. We could blast them with everything we had, and they'd just soak it up and laugh at us and ask for more."
   He skidded the jumper around a ravine head, slashed across the desert. "First thing," he declared, "is to find the one that's masquerading as Knut. Find him and then figure out what to do with him."
   But finding the Knut Candle was easier said than done. Craig, Creepy and Rastus, clad in spacesuits, stood in the kitchen at the Centre.
   "By cracky," said Creepy, "he must be here somewhere. He must have found him an extra-special hideout that we have overlooked."
   Craig shook his head. "We haven't overlooked him, Creepy. We've searched this place from stem to stern. There isn't a crack where he could hide."
   "Maybe," suggested Creepy, "he figured the jig was up and took it on the lam. Maybe he scrammed out the lock when I was up there guarding that control room."
   "Maybe," agreed Craig. "I had been thinking of that. He smashed the radio - that much we know. He was afraid that we might call for help, and that means he may have had a plan. Even now he may be carrying out that plan."
   The Centre was silent, filled with those tiny sounds that only serve to emphasise and deepen a silence. The faint cluck-cluck of the machines on the floor below, the hissing and distant chortling of the atmosphere mixer, the chuckling of the water synthesizer.
   "Dang him," snorted Creepy, "I knew he couldn't do it. I knew Knut couldn't beat me at checkers honest —"
   From the refrigerator came a frantic sound. "Me-ow -me-ow-ow-ow," it wailed.
   Rastus leaped for the refrigerator door, grabbing a broom as he went. "It's that Mathilde cat again," he yelled. "She's always sneakin' in on me. Every time my back is turned."
   He brandished the broom and addressed the door. "You jus' wait. I'll sure work you over with this here broom. I'll plaster you —"
   But Craig had leaped forward, snatched the Negro's hand away from the door. "Wait!" he shouted.
   Mathilde yodelled pitifully.
   "But, boss, that Mathilde cat —"
   "Maybe it isn't Mathilde," Craig rasped grimly.
   From the doorway leading out into the corridor came a low purring rumble. The three men whirled about. Mathilde was standing across the threshold, rubbing with arched back against the jamb, plumed tail waving. From inside the refrigerator came a scream of savage feline fury.
   Rastus's eyes were popping and the broom clattered to the floor. "But, boss," he shrieked, "there's only one Mathilde!"
   "Of course, there's only one Mathilde," snapped Craig. "One of these is her. The other is Knut, or the thing that was Knut."
   The lock signal rang shrilly, and Craig stepped swiftly to a port, flipped the shutter up.
   "It's Page," he shouted. "Page is back again!"
   He turned from the port, face twisted in disbelief. Page had gone out five hours before - without oxygen. Yet here he was, back again. No man could live for over four hours without oxygen.
   Craig's eyes hardened, and furrows came between his brows.
   "Creepy," he said suddenly. "You open the inner lock. You, Rastus, pick up that cat. Don't let her get away."
   Rastus backed off, eyes wide in terror.
   "Pick her up," commanded Craig sharply. "Hang onto her."
   "But, boss, she —"
   "Pick her up, I say!"
   Creepy was shuffling down the ramp to the lock. Slowly Rastus moved forward, clumsily reached down and scooped up Mathilde. Mathilde purred loudly, dabbing at his suit-clad fingers with dainty paws.
   Page stepped out of the jumper and strode across the garage toward Craig, his boot heels ringing on the floor.
   From behind the spacesuit visor, Craig regarded him angrily. "You disobeyed my orders," he snapped. "You went out. and caught some Candles."
   "Nothing to it, Captain Craig," said Page. "Docile as so many kittens. Make splendid pets."
   He whistled sharply, and from the open door of the jumper rolled three Candles, a red one, a green one, a yellow one. Ranged in a row, they lay just outside the jumper, rolling back and forth.
   Craig regarded them appraisingly.
   "Cute little devils," said Page good-naturedly.
   "And just the right number," said Craig.
   Page started, but quickly regained his composure. "Yes, I think so, too. I'll teach them a routine, of course, but I suppose the audience reactions will bust that all to hell once they get on the stage."
   Craig moved to the rack of oxygen tanks and snapped up the lid.
   "There's just one thing I can't understand," he said. "I warned you you couldn't get into this rack. And I warned you that without oxygen you'd die. And yet here you are."
   Page laughed. "I had some oxygen hid out, Captain. I anticipated something just like that."
   Craig lifted one of the tanks from the rack, held it in his arms. "You're a liar, Page," he said calmly. "You didn't have any other oxygen. You didn't need any. A man would die if he went out there without oxygen - die horribly. But you wouldn't - because you aren't a man\"
   Page stepped swiftly back, but Craig cried out warningly. Page stopped, as if frozen to the floor, his eyes on the oxygen tank. Craig's finger grasped the valve control.
   "One move out of you," he warned grimly, "and I'll let you have it. You know what it is, of course. Liquid oxygen, pressure of two hundred atmospheres. Colder than the hinges of space."
   Craig grinned ferociously. "A dose of that would play hell with your metabolism, wouldn't it? Tough enough to keep going here in the dome. You Candles have lived out there on the surface too long. You need a lot of energy, and there isn't much energy here. We have to screen it out or we would die ourselves. And there's a damn sight less energy in liquid oxygen. You met your own environment, all right; you even spread that environment pretty wide, but there's a limit to it."
   "You'd be talking a different tune," Page declared bitterly, "if it weren't for those spacesuits."
   "Sort of crossed you up, didn't they," said Craig. "We're wearing them because we were tracking down a pal of yours. I think he's in the refrigerator."
   "A pal of mine - in a refrigerator?"
   "He's the one that came back as Knut," said Craig, "and he turned into Mathilde when he knew we were hunting for him. But he did the job too well. He was almost more Mathilde than he was Candle. So he sneaked into the refrigerator. And he doesn't like it."
   Page's shoulders sagged. For a moment his features seemed to blur, then snapped back into rigid lines again.
   "The answer is that you do the job too well," said Craig. "Right now you yourself are more Page than Candle, more man than thing of energy."
   "We shouldn't have tried it," said Page. "We should have waited until there was someone in your place. You were too frank in your opinion of us. You held none of the amused contempt so many of the others held. I told them they should wait, but a man named Page got caught in a space warp —"
   Craig nodded. "I understand. An opportunity you simply couldn't miss. Ordinarily we're pretty hard to get at. You can't fight photocells. But you should strive for more convincing stories. That yarn of yours about capturing Candles —"
   "But Page came out for that purpose," insisted the pseudo-Page. "Of course, he would have failed. But, after all, it was poetic justice."
   "It was clever of you," Craig said softly. "More clever than you thought. Bringing your sidekicks in here, pretending you had captured them, waiting until we were off our guard."
   "Look," said Page, "we know when we are licked. What are you going to do?"
   "We'll turn loose the one in the refrigerator," Craig told him. "Then we'll open up the locks and you can go."
   "And if we don't want to go?"
   "We'd turn loose the liquid oxygen," said Craig. "We have vats of the stuff upstairs. We can close off this room, you know, turn it into a howling hell. You couldn't live through it. You'd starve for energy."
   From the kitchen came a hideous uproar, a sound that suggested a roll of barbed wire galloping around a tin roof. The bedlam was punctuated by yelps and howls from Rastus.
   Creepy, who had been standing by the lock, started forward, but Craig, never lifting an eye from Page, waved him back.
   Down the ramp from the kitchen came a swirling ball of fur, and after it came Rastus, whaling lustily with his broom, the ball of fur separated, became two identical cats, tails five times normal size, backs bristling, eyes glowing with green fury.
   "Boss, I jus' got tired of holding Mathilde —" Rastus panted.
   "I know," said Craig. "So you chucked her into the refrigerator with the other cat."
   "I sho' did," confessed Rastus, "and hell busted loose right underneath my nose."
   "All right," snapped Craig. "Now, Page, if you'll tell us which one of those is yours —"
   Page spoke sharply and one of the cats melted and flowed. Its outlines blurred and it became a Candle, a tiny, pale-pink Candle.
   Mathilde let out one soul-wrenching shriek and fled.
   "Page," said Craig, "we've never wanted trouble. If you are willing we'd like to be your friends. Isn't there some way?"
   Page shook his head. "No, Captain. We're poles apart. I and you have talked here, but we've talked as man to man rather than as a man and a person of my race. Our differences are too great, our minds too far apart."
   He hesitated, almost stammering. "You're a good egg, Craig. You should have been a Candle."
   "Creepy," said Craig, "open up the lock."
   Page turned to go, but Craig called him back. "Just one thing more. A personal favour. Could you tell me what's at the bottom of this?"
   "It's hard to explain," said Page. "You see, my friend, it's a matter of culture. That isn't exactly the word, but it's the nearest I can express it in your language.
   "Before you came we had a culture, a way of life, a way of thought, that was distinctly our own. We didn't develop the way you developed, we missed this crude, preliminary civilisation you are passing through. We started at a point you won't reach for another million years.
   "We had a goal, an ideal, a place we were heading for. And we were making progress. I can't explain it, for - well, there just are no words for it. And then you came along —"
   "I think I know," said Craig. "We are a disturbing influence. We have upset your culture, your way of thought. Our thoughts intrude upon you and you see your civilisation turning into a troupe of mimics, absorbing alien ideas, alien ways."
   He stared at Page. "But isn't there a way? Damn it, do we have to fight about this?"
   But even as he spoke, he knew there was no way. The long role of terrestrial history recorded hundreds of such wars as this - wars fought over forms of faith, over terminology of religion, over ideologies, over cultures. And the ones who fought those wars were members of the same race - not members of two races separated by different origins, by different metabolisms, by different minds.
   "No," he said, "there is no way. Some day, perhaps, we will be gone. Some day we will find another and a cheaper source of power and you will be left in peace. Until that day —" he left the words unspoken.
   Page turned away, headed for the lock, followed by the three big Candles and the little pink one.
   Ranged together at the port, the three Terrestrials watched the Candles come out of the lock. Page was still in the form of a man, but as he walked away the form ran together and puddled down until he was a sphere.
   Creepy cackled at Craig's elbow. "By cracky," he yelped, "he was a purple one!"
   Craig sat at his desk, writing his report to the Solar power board, his pen travelling rapidly over the paper:
   
    - they waited for 500 years before they acted. Perhaps this was merely caution or in the hope they might find a better way. Or it may be that time has a different value for them than it has for us. In an existence which stretches into eternity, time would have but little value.
    For all those 500 years they have watched and studied us. They have read our minds, absorbed our thoughts, dug out our knowledge, soaked up our personalities. Perhaps they know us better than we know ourselves. Whether their crude mimicry of our thoughts is merely a clever ruse to make us think they are harmless or whether it reflects differing degrees of the art of mimicry - the difference between a cartoon and a masterpiece of painting - I cannot say. I cannot even guess.
    Heretofore we have never given thought to protect ourselves against them, for we have considered them, in general, as amusing entities and little else. Whether or not the cat in the refrigerator was the Candle or Mathilde I do not know, but it was the cat in the refrigerator that gave me the idea of using liquid oxygen. Undoubtedly there are better ways. Anything that would swiftly deprive them of energy would serve. Convinced they will try again, even if they have to wait another 500 years, I urgently suggest—
   
   He stopped and laid down the pen.
   From the kitchen below came the faint clatter of pots and pans as Rastus engineered- a dinner. Bellowed snatches of unmusical song, sandwiched between the clatter of utensils, floated up the ramp:
   "Chicken in de bread pan, Kickin' up de dough —"
   The wastebasket in the corner moved slightly and Mathilde slunk out, tail at half mast. With a look of contempt at Craig, she stalked to the door and down the ramp.
   Creepy was tuning up his fiddle, but only half-heartedly. Creepy felt badly about Knut. Despite their checker arguments, the two had been good friends.
   Craig considered the things he'd have to do. He'd have to go out and bring in Knut's body, ship it back to Earth for burial. But first he was going to sleep. Lord, how he needed sleep!
   He picked up the pen and proceeded with his writing:
    - that every effort be bent to the development of some convenient weapon to be used against them. But to be used only in defence. A program of extermination, such as has been carried out on other planets, is unthinkable.
    To do this it will be necessary that we study them even as they have studied us. Before we can fight them we must know them. For the next time their method of attack undoubtedly will be different.
    Likewise we must develop a test, to be applied to every person before entering the Centre, that will reveal whether he is a Candle or a man.
    And, lastly, every effort should be made to develop some other source of universal power against the day when Mercury may become inaccessible to us.
   He reread the report and put it down.
   "They won't like that," he told himself. "Especially that last paragraph. But we have to face the truth."
   Rastus's voice rose shrilly. "You, Mathilde! You get out of there! Can't turn my back but you're in that icebox —"
   A broom thudded with a whack.
   There was no sound from the control room. Creepy apparently had put away his fiddle. Probably didn't have the heart to play it.
   For a long time Craig sat at his desk, thinking. Then he arose and went to the port.
   Outside, on the bitter plains of Mercury, the Candles had paired off, two and two, were monstrous dice, rolling in the dust. As far as the eye could see, the plains were filled with galloping dominoes.
   And every pair, at every toss, were rolling sevens!