The corridor down which they moved this time was one that might have been familiar even in Dave's Chicago. There was the sound of typewriters from behind the doors, and the floor was covered with composition tile, instead of the too-lush carpets. He began to relax a little until he came to two attendants busily waxing the floor. One held the other by the ankles and pushed the creature's hairy face back and forth, while its hands spread the wax ahead of it. The results were excellent, but Dave found it hard to appreciate.

Ser Perth shrugged slightly. "They're only mandrakes," he explained. He threw open the door of one of the offices and led them through an outer room toward an inner chamber, equipped with comfortable chairs and a desk. "Sit down, Dave Hanson. I'll fill you in on anything you need to know before you're assigned. Now—the Sather Karf told you what you were to do, of course, but—"

"Wait a minute," Dave suggested. "I don't remember being told any such thing."

Ser Perth looked at Nema, who nodded. "He distinctly said you were to repair the sky. I've got it down in my notes if you want to see them." She extended the woven cords.

"Never mind," Ser Perth said. He twiddled with his mustache. "I'll recap a little. Dave Hanson, as you have seen, the sky is falling and must be repaired. You are our best hope. We know that from a prophecy, and it is confirmed by the fact that the fanatics of the Egg have tried several times to kill you. They failed, though one effort was close enough, but their attempts would not have been made at all if they had not been convinced through their arts that you can succeed with the sky."

Dave shook his head. "It's nice to know you trust me!"

"Knowing that you can succeed," the other went on smoothly, "we know that you will. It is my unpleasant duty to point out to you the things that will happen if you fail. I say nothing of the fact that you owe us your life; that may be a small enough gift, and one quickly withdrawn. I say only that you have no escape from us. We have your name, and the true symbol is the thing, as you should know. We also have cuttings from your hair and your beard; we have the parings of your nails, five cubic centimeters of your spinal fluid and a scraping from your liver. We have your body through those, nor can you take it out of our reach. Your name gives us your soul." He looked at Hanson piercingly. "Shall I tell you what it would be like for your soul to live in the muck of a swamp in a mandrake root?"

Dave shook his head. "I guess not. I—look, Ser Perth. I don't know what you're talking about. How can I go along with you when I'm in the dark? Start at the beginning, will you? I was killed; all right, if you say I was, I was. You brought me to life again with a mandrake root and spells; you can do anything you want with me. I admit it; right now, I'll admit anything you want me to, because you know what's going on and I don't. But what's all this business of the sky falling? If it is and can be falling, what's the difference? If there is a difference, why should I be able to do anything about it?"

"Ignorance!" Ser Perth murmured to himself. He sighed heavily. "Always ignorance. Well, then, listen." He sat down on the corner of the desk and took out a cigarette. At least it looked like a cigarette. He snapped his fingers and lighted it from a little flame that sprang up, blowing clouds of bright green smoke from his mouth. The smoke hung lazily, drifting into vague patterns and then began to coalesce into a green houri without costume. He swatted at it negligently.

"Dratted sylphs. There's no controlling the elementals properly any more." He didn't seem too displeased, however, as he watched the thing dance off. Then he sobered.

"In your world, Dave Hanson, you were versed in the engineering arts—you more than most. That you should be so ignorant, though you were considered brilliant is a sad commentary on your world. But no matter. Perhaps you can at least learn quickly still. Even you must have had some idea of the composition of the sky?"

Dave frowned as he tried to answer. "Well, I suppose the atmosphere is oxygen and nitrogen, mostly; then there's the ionosphere and the ozone layer. As I remember, the color of the sky is due to the scattering of light—light rays being diffracted in the air."

"Beyond the air," Ser Perth said impatiently. "The sky itself!"

"Oh—space. We were just getting out there with manned ships. Mostly vacuum, of course. Of course, we're still in the solar atmosphere, even there, with the Van Allen belts and such things. Then there are the stars, like our sun, but much more distant. The planets and the moon—"

"Ignorance was bad enough," Ser Perth interrupted in amazement. He stared at Dave, shaking his head in disgust. "You obviously come from a culture of even more superstition than ignorance. Dave Hanson, the sky is no such thing. Put aside the myths you heard as a child. The sky is a solid sphere that surrounds Earth. The stars are no more like the sun than the glow of my cigarette is like a forest fire. They are lights on the inside of the sphere, moving in patterns of the Star Art, nearer to us than the hot lands to the south."

"Fort," Dave said. "Charles Fort said that in a book."

Ser Perth shrugged. "Then why make me say it again? This Fort was right. At least one intelligent man lived in your world, I'm pleased to know. The sky is a dome holding the sun, the stars and the wandering planets. The problem is that the dome is cracking like a great, smashed eggshell."

"What's beyond the dome?"

Ser Perth shuddered slightly. "My greatest wish is that I die before I learn. In your world, had you discovered that there were such things as elements? That is, basic substances which in combination produce—"

"Of course," Dave interrupted.

"Good. Then of the four elements—" Dave gulped, but kept silent, "—of the four elements the universe is built. Some things are composed of a single element; some of two, some of three. The proportions vary and the humors and spirits change but all things are composed of the elements. And only the sky is composed of all four elements—of earth, of water, of fire and of air—in equal proportions. One part each, lending each its own essential quality to the mixture, so that the sky is solid as earth, radiant as fire, formless as water, insubstantial as air. And the sky is cracking and falling, as you have seen for yourself. The effects are already being felt. Gamma radiation is flooding through the gaps; the quick-breeding viruses are mutating through half the world, faster than the Medical Art can control them, so that millions of us are sneezing and choking—and dying, too, for lack of antibiotics and proper care. Air travel is a perilous thing; just today, a stratosphere roc crashed head-on into a fragment of the sky and was killed with all its passengers. Worst of all, the Science of Magic suffers. Because the stars are fixed on the dome of the sky. With the crumbling of that dome, the course of the stars has been corrupted. It's pitiful magic that can be worked without regard to the conjunctions of the planets; but it is all the magic that is left to us. When Mars trines Neptune, the Medical Art is weak; even while we were conjuring you, the trine occurred. It almost cost your life. And it should not have occurred for another seven days."

There was silence, while Ser Perth let Dave consider it. But it was too much to accept at once, and Dave's mind was a treadmill. He'd agreed to admit anything, but some of this was such complete nonsense that his mind rejected it automatically. Yet he was sure Ser Perth was serious; there was no humor on the face of the prissy thin-mustached man before him. Nor had the Sather Karf considered it a joke, he was sure. He had a sudden vision of the latter strangling two men from a distance of thirty feet without touching them. That couldn't happen in a sane world, either.

Dave asked weakly, "Could I have a drink?"

"With a sylph around?" Ser Perth grimaced. "You wouldn't have a chance. Now, is all clear to you, Dave Hanson?"

"Sure. Except for one thing. What am I supposed to do?"

"Repair our sky. It should not be too difficult for a man of your reputation. You built a wall across a continent high and strong enough to change the air currents and affect all your weather—and that in the coldest, meanest country in your world. You come down to us as one of the greatest engineers of history, Dave Hanson, so great that your fame has penetrated even to our world, through the viewing pools of our wisest historians. There is a shrine and monument in your world. 'Dave Hanson, to whom nothing was impossible.' Well, we have a nearly impossible task: a task of engineering and building. If our Science of Magic could be relied upon—but it cannot; it never can be, until the sky is fixed. We have the word of history: no task is impossible to Dave Hanson."

Dave looked at the smug face and a slow grin crept over his own, in spite of himself. "Ser Perth, I'm afraid you've made a slight mistake."

"We don't make mistakes in such matters. You're Dave Hanson," Ser Perth said flatly. "Of all the powers of the Science, the greatest lies in the true name. We evoked you by the name of Dave Hanson. You are Dave Hanson, therefore."

"Don't try to deceive us," Nema suggested. Her voice was troubled. "Pray rather that we never have reason to doubt you. Otherwise the wisest of the Satheri would spend their remaining time in planning something unthinkable for you."

Ser Perth nodded vigorous assent. Then he motioned to the office. "Nema will show you to your quarters later. Use this until you leave. I have to report back."

Dave stared after him until he was gone, and then around at the office. He went to the window and stared upwards at the crazy patchwork of the sky. For all he knew, in such a sky there might be cracks. In fact, as he looked, he could make out a rift, and beyond that a ... hole ... a small patch where there was no color, and yet the sky there was not black. There were no stars there, though points of light were clustered around the edges, apparently retreating.

All he had to do was to repair the sky. Shades of Chicken Little!

Maybe to David Arnold Hanson, the famed engineer, no task was impossible. But quite a few things were impossible to that engineer's obscure and unimportant nephew, the computer technician and generally undistinguished man who had been christened Dave. They'd gotten the right man for the name, all right. But the wrong man for the job.

Dave Hanson could repair anything that contained electrical circuits or ran on tiny jeweled bearings, but he could handle almost nothing else. It wasn't stupidity or incapacity to learn, but simply that he had never been subjected to the discipline of construction engineering. Even on the project, while working with his uncle, he had seen little of what went on, and hadn't really understood that, except when it produced data that he could feed into his computer. He couldn't drive a nail in the wall to hang a picture or patch a hole in the plaster.

But it seemed that he'd better put on a good show of trying if he wanted to continue enjoying good health.

"I suppose you've got a sample of the sky that's fallen?" he asked Nema. "And what the heck are you doing here, anyhow? I thought you were a nurse."

She frowned at him, but went to a corner where a small ball of some clear crystalline substance stood. She muttered into it, while a surly face stared out. Then she turned back to him, nodding. "They are sending some of the sky to you. As to my being a nurse, of course I am. All student magicians take up the Medical Art for a time. Surely one so skilled can also be a secretary, even to the great Dave Hanson? As to why I'm here—" She dropped her eyes, frowning, while a touch of added color reached her cheeks. "In the sleep spell I used, I invoked that you should be well and true. But I'm only a bachelor in magic, not even a master, and I slipped. I phrased it that I wanted you well and true. Hence, well and truly do I want you."

"Huh?" He stared at her, watching the blush deepen. "You mean—?"

"Take care! First you should know that I am proscribed as a duly registered virgin. And in this time of need, the magic of my blood must not be profaned." She twisted sidewise, and then turned toward the door, avoiding him. Before she reached it, the door opened to show a dull clod, entirely naked, holding up a heavy weight of nothing.

"Your sample of sky," she said as the clod labored over to the desk and dropped nothing with a dull clank. The desk top dented slightly.

Dave could clearly see that nothing was on the desk. But if nothing was a vacuum, this was an extremely hard and heavy one. It seemed to be about twelve inches on a side, in its rough shape, and must have weighed two hundred pounds. He tapped it, and it rang. Inside it, a tiny point of light danced frantically back and forth.

"A star," she said sadly.

"I'm going to need some place to experiment with this," he suggested. He expected to be sent to the deepest, dankest cave of all the world as a laboratory, and to find it equipped with pedigreed bats, dried unicorn horns and whole rows of alembics that he couldn't use.

Nema smiled brightly. "Of course. We've already prepared a construction camp for you. You'll find most of the tools you used in your world waiting there and all the engineers we could get or make for you."

He'd been considering stalling while he demanded exactly such things. He was reasonably sure by now that they had no transistors, signal generators, frequency meters or whatever else he could demand. He could make quite an issue out of the need to determine the characteristic impedance of their sky. That might even be interesting, at that; would it be anywhere near 300 ohms here? But it seemed that stalling wasn't going to work. They'd given him what they expected him to need, and he'd have to be careful to need only what they expected, or they might just decide he wasn't Dave Hanson.

"I can't work on this stuff here," he said.

"Then why didn't you say so?" she asked sharply. She let out a cry and a raven came flying in. She whispered something to it, frowned, and then ordered it off. "There's no surface transportation available, and all the local rocs are in use. Well, we'll have to make do with what we have."

She darted for the outer office, rummaged in a cabinet, and came back with a medium-sized rug of worn but gaudy design. Bad imitation Sarouk, Dave guessed. She tossed it onto the largest cleared space, gobbled some outlandish noises, and dropped onto it, squatting near one end. Behind her, the dull clod picked up the sample of sky and fell to his face on the rug. At her vehement signal, Dave squatted down beside her, not daring to believe what he was beginning to guess.

The carpet lifted uncertainly. It seemed to protest at the unbalanced weight of the sky piece. She made the sounds again, and it rose reluctantly, curling up at the front, like a crazy toboggan. It moved slowly, but with increasing speed, sailed out of the office through the window and began gaining altitude. They went soaring over the city at about thirty miles an hour, heading toward what seemed to be barren land beyond. "Sometimes they fail now," she told him. "But so far, only if the words are improperly pronounced."

He gulped and looked gingerly over at the city below. As he did, she gasped. He heard a great tearing sound of thunder. In the sky, a small hole appeared. There was a scream of displaced air, and something went zipping downwards in front of them, setting up a wind that bounced the carpet about crazily. Dave glanced over the edge again to see one of the tall buildings crumple under the impact. The three top stories were ripped to shreds. Then the whole building began to change. It slowly blossomed into a huge cloud of pink gas that rifted away, to show people and objects dropping like stones to the ground below. Nema sighed and turned her eyes away.

"But—it's ridiculous!" Dave protested. "We heard the rip and less than five seconds later, that piece fell. If your sky is even twenty miles above us, it would take longer than that to fall."

"It's a thousand miles up," she told him. "And sky has no inertia until it is contaminated by contact with the ground. It took longer than usual for that piece to fall." She sighed. "It gets worse. Look at the signs. That break has disturbed the planets. We're moving retrograde, back to our previous position, out of Sagittarius! Now we'll go back to the character we had before—and just when I was getting used to the change."

He jerked his eyes off the raw patch of emptiness in the sky, where a few stars seemed to be vanishing. "Your character? Isn't anything stable here?"

"Of course not. Naturally, in each House we have a differing of character, as does the world itself. Why else should astrology be the greatest of the sciences?"

It was a nice world, he decided. And yet the new factor explained some things. He'd been vaguely worried about the apparent change in Ser Perth, who'd turned from a serious and helpful doctor into a supercilious, high-handed fop. But—what about his recovery, if that was supposed to be determined by the signs of the zodiac?

He had no time to ask. The carpet bucked, and the girl began speaking to it urgently. It wavered, then righted itself, to begin sliding downwards.

"There is a ring of protection around your camp," Nema explained. "It is set to make entry impossible to one who does not have the words or who is unfriendly. The carpet could not go through that, anyway. The ring negates all other magic trying to pass it. And of course we have basilisks mounted on posts around the grounds. They're trained to hood their eyes, except when they sense anyone trying to enter who should not. You can't be turned to stone looking at one, you know—only by having one look at you."

"You're cheering me up no end," he assured her.

She smiled pleasantly and began setting the carpet down. Below, he could see a camp that looked much like the camps he had seen in the same movies from which all his clothes had been copied. There were well laid-out rows of sheds, beautiful lines of construction equipment and everything in order, as it could never be in a real camp. As he began walking with the girl toward a huge tent that should have belonged to a circus, he could see other discrepancies. The tractors were designed for work in mud flats and the haulers had the narrow wheels used on rocky ground. Nothing seemed quite as it should be. He spotted a big generator working busily—and then saw a gang of about fifty men, or mandrakes, turning a big capstan that kept it going. Here and there were neat racks of miscellaneous tools. Some were museum pieces. There was even a gandy cart, though no rails for it to run on.

They were almost at the main tent when a crow flew down and yelled something in Nema's ear. She scowled, and nodded. "I'm needed back," she said. "Most of the men here—" She pointed to the gangs that moved about busily doing nothing, all in costumes similar to his, except for the boots and hat. "They're mandrakes, conjured into existence, but without souls. The engineers we have are snatched from Duality just after dying and revived here while their brains still retain their knowledge. They have no true souls either, of course, but they don't know it. Ah. The short man there—he's Garm. Sersa Garm, an apprentice to Ser Perth. He's to be your foreman, and he's real."

She headed back to the outskirts, then turned to shout back. "Sather Karf says you may have ten days to fix the sky," she called. Her hand waved toward him in friendly good-bye. "Don't worry, Dave Hanson. I have faith in you."

Then she was running toward her reluctant carpet.

Dave stared up at the mottled dome above him and at the dull clod—certainly a mandrake—who was still carrying the sample. With all this preparation and a time limit, he couldn't even afford to stall. He'd never fully understood why some plastics melted and others turned hard when heated, but he had to find what was wrong with the dome above and how to fix it. And maybe the time limit could be stretched a little, once he came up with the answer. Maybe. He'd worry about that after he worried about the first steps.

Sersa Garm proved to be a glum, fat young man, overly aware of his importance in training for serhood. He led Dave through the big tent, taking pride in the large drafting section—under the obvious belief that it was used for designing spells. Maybe it could have been useful for that if there had been a single man who knew anything about draftsmanship. There were four engineers, supposedly. One, who had died falling off a bridge while drunk, was curing himself of the shock by remaining dead drunk. One had been a chemical engineer specializing in making yeast and dried soya meal into breakfast cereals. Another knew all about dredging canals and the last one was an electronics engineer—a field in which Dave was far more competent.

He dismissed them. Whatever had been done to them—or perhaps the absence of a true soul, whatever that was—left them rigidly bound to their past ideas and totally incapable of doing more than following orders by routine now. Even Sersa Garm was more useful.

That young man could offer little information, however. The sky, he explained pompously, was a great mystery that only an adept might communicate to another. He meant that he didn't know about it, Dave gathered. Everything, it turned out, was either a mystery or a rumor. He also had a habit of sucking his thumb when pressed too hard for details.

"But you must have heard some guesses about what started the cracks in the sky?" Dave suggested.

"Oh, indeed, that is common knowledge," Sersa Garm admitted. He changed thumbs while he considered. "'Twas an experiment most noble, but through mischance going sadly awry. A great Sather made the sun remain in one place too long, and the heat became too great. It was like the Classic experiment—"

"How hot is your sun?"

There was a long pause. Then Sather Germ shrugged. "'Tis a great mystery. Suffice to say it has no true heat, but does send forth an activating principle against the phlogiston layer, which being excited grows vengeful against the air ... but you have not the training to understand."

"Okay, so they didn't tell you, if they knew." Dave stared up at the sun, trying to guess. The light looked about like what he was used to, where the sky was still whole. North light still was like what a color photographer would consider 5500° Kelvin, so the sun must be pretty hot. Hot enough to melt anything he knew about. "What's the melting point of this sky material?"

He never did manage to make Sather Garm understand what a melting point was. But he found that one of the solutions tried had been the bleeding of eleven certified virgins for seven days. When the blood was mixed with dragonfeathers and frogsdown and melded with a genuine philosopher's stone, they had used it to ink in the right path of the planets of a diagram. It had failed. The sky had cracked and a piece had fallen into the vessel of blood, killing a Sather who was less than two thousand years old.

"Two thousand?" Dave asked. "How old is Sather Karf?"

"None remembers truly. He has always been the Sather Karf—at least ten thousand years or more. To attain the art of a Sather is the work of a score of centuries, usually."

That Sather had been in sad shape, it seemed. No one had been able to revive him, though bringing the dead back to life when the body was reasonably intact was routine magic that even a sersa could perform. It was after that they'd begun conjuring back to Dave's world for all the other experts.

"All whose true names they could find, that is," Garm amended. "The Egyptian pyramid builder, the man who discovered your greatest science, dianetics, the great Cagliostro—and what a time we had finding his true name! I was assigned to the helping of one who had discovered the secrets of gravity and some strange magic which he termed relativity—though indeed it had little to do with kinship, but was a private mystery. But when he was persuaded by divers means to help us, he gave up after one week, declaring it beyond his powers. They were even planning what might best be done to chastise him when he discovered in some manner a book of elementary conjuration and did then devise some strange new formula from the elements with which magic he disappeared."

It was nice to know that Einstein had given up on the problem, Dave thought bitterly. As nice as the discovery that there was no fuel for the equipment here. He spent an hour rigging up a portable saw to use in attempting to cut off a smaller piece of the sky, and then saw the motor burn out when he switched it on. It turned out that all electricity here was d.c., conjured up by commanding the electrons in a wire to move in one direction, and completely useless with a.c. motors. It might have been useful for welding, but there was no electric torch.

"'Tis obviously not a thing of reason," Garm told him severely. "If the current in such a form moves first in one direction and then in the other, then it cancels out and is useless. No, you must be wrong."

As Dave remembered it, Tesla had been plagued by similar doubts from such men as Edison. He gave up and settled finally for one of the native welding torches, filled with a dozen angry salamanders. The flame or whatever it was had enough heat, but it was hard to control. By the time he learned to use it, night had fallen, and he was too tired to try anything more. He ate a solitary supper and went to sleep.

During the next three days he learned a few things the hard way, however. In spite of Garm's assurance that nothing could melt the sky, he found that his sample would melt slowly under the heat of the torch. In the liquid state, it was jet black, though it cooled back to complete transparency. It was also without weight when in liquid form—a fact he discovered when it began rising through the air and spattering over everything, including his bare skin. The burns were nasty, but somehow seemed to heal with remarkable speed. Sersa Garm was impressed by the discoveries, and went off to suck his thumbs and brood over the new knowledge, much to Dave's relief.

More work established the fact that welding bits of the sky together was not particularly difficult. The liquid sky was perfectly willing to bond onto anything, including other bits of itself.

Now, if he could get a gang up the thousand miles to the sky with enough torches to melt the cracks, it might recongeal as a perfect sphere. The stuff was strong, but somewhat brittle. He still had no idea of how to get the stars and planets back in the right places.

"The mathematician thought of such an idea," Sersa Garm said sourly. "But 'twould never work. Even with much heat, it could not be done. For see you, the upper air is filled with phlogiston, which no man can breathe. Also, the phlogiston has negative weight, as every school child must know. Your liquid sky would sink through it, since negative weight must in truth be lighter than no weight, while nothing else would rise through the layer. And phlogiston will quench the flame of a rocket, as your expert von Braun discovered."

The man was a gold mine of information, all bad. The only remaining solution, apparently, was to raise a scaffolding over the whole planet to the sky, and send up mandrakes to weld back the broken pieces. They wouldn't need to breathe, anyhow. With material of infinite strength—and an infinite supply of it—and with infinite time and patience, it might have been worth considering.

Nema came out the next day with more cheering information. Her multi-times great grandfather, Sather Karf, regretted it, but he must have good news to release at once; the populace was starving because the food multipliers couldn't produce reliable supplies. Otherwise, Dave would find venom being transported into his blood in increasing amounts until the pain drove him mad. And, just incidentally, the Sons of the Egg who'd attacked him in the hospital had tried to reach the camp twice already, once by interpenetrating into a shipment of mandrakes, which indicated to what measures they would resort. They meant to kill him somehow, and the defense of him was growing too costly unless there were positive results.

Dave hinted at having nearly reached the solution, giving her only a bit of his wild idea of welding the sky. She took off with that, but he was sure it wouldn't satisfy the Sather. In that, he was right. By nightfall, when she came back from the city, he was groaning in pain. The venom had arrived ahead of her, and his blood seemed to be on fire.

She laid a cool hand on his forehead. "Poor Dave," she said. "If I were not registered and certified, sometimes I feel that I might ... but no more of that. Ser Perth sends you this unguent which will hold back the venom for a time, cautioning you not to reveal his softness." Ser Perth, it seemed, had reverted to his pre-Sagittarian character as expected. "And Sather Karf wants the full plans at once. He is losing patience."

He began rubbing on the ointment, which helped slightly. She peeled back his shirt and began helping, apparently delighted with the hair which he'd sprouted on his chest since his reincarnation. The unguent helped, but it wasn't enough.

"He never had any patience to lose. What the hell does he expect me to do?" Dave asked hotly. "Snap my fingers thus, yell abracadabra and give him egg in his beer?"

He stopped to stare at his hand, where a can of beer had suddenly materialized!

Nema squealed in delight. "What a novel way to conjure, Dave. Let me try it." She began snapping her fingers and saying the word eagerly, but nothing happened. Finally she turned back to him. "Show me again."

He was sure it wouldn't work twice, and he hesitated, not too willing to have his stock go down with her. Then he gave in.

"Abracadabra!" he said, and snapped his fingers.

There were results at once. This time an egg appeared in his hand, to the delighted cry of Nema. He bent to look at it uncertainly. It was a strange looking egg—more like one of the china eggs used to make hens think they were nesting when their eggs were still being taken from them.

Abruptly Nema sprang back. But she was too late. The egg was growing. It swelled to the size of a football, then was man-sized, and growing to the size of a huge tank that filled most of the tent. Suddenly it split open along one side and a group of men in dull robes and masks came spilling out of it.

"Die!" the one in front yelled. He lifted a double-bladed knife, charged for Dave, and brought the knife down.

The blades went through clothing, skin, flesh and bones, straight for Dave's heart.