They all heard the steely squeak of a car's wheel. Up the mother shaft, past cross tunnel Forty; had to be foremen at this time of shift. Would the car turn at the fork to their concourse? Their hypersensitive ears focused on the distant sound; no one breathed. The wheels squeaked, turned their way. Oliver, who was already shivering, began to shake hard.

  The car stopped before their pen. The door opened, all in darkness. Not a sound from the quaking miners.

  Fierce white light blasted them and they cried out, leaped back against the cage bars vainly. Blinded, Oliver cringed at the clawing of a foreman's hands, searching under his shirt and pants. Through pupils like pinholes he glimpsed brief black-and-white snapshots of gaunt bodies undergoing similar searches, then blows. Shouts, cries of pain, smack of flesh on flesh, an electric buzzing. Shaving their heads, could it be that time again already? He was struck in the stomach, choked around the neck. Hester's long wiry brown arms, wrapped around her head. Scalp burned, buzzz all chopped up. Thrown to the rock.

  "Where's the twelfth?" In the foremen's staccato language. No one answered.

  The foremen left, light receding with them until it was black again, the pure dense black that was their own. Except now it was swimming with bright red bars, washing around in painful tears. Oliver's third eye opened a little, which calmed him, because it was still a new experience; he could make out his companions, dim redblack shapes in the black, huddled over themselves, gasping.

  Jakob moved among them, checking for hurts, comforting. He cupped Oliver's forehead and Oliver said, "It's seeing already."

  "Good work." On his knees Jakob clumped to their shit bucket, took off the lid, reached in. He pulled something out. Oliver marveled at how clearly he was able to see all this. Before, floating blobs of color had drifted in the black; but he had always assumed they were afterimages, or hallucinations. Only with Jakob's instruction had he been able to perceive the patterns they made, the vision that they constituted. It was an act of will. That was the key.

  Now, as Jakob cleaned the object with his urine and spit, Oliver found that the eye in his forehead saw even more, in sharp blood etchings. Jakob held the lump overhead, and it seemed it was a little lamp, pouring light over them in a wavelength they had always been able to see, but had never needed before. By its faint ghostly radiance the whole pen was made clear, a structure etched in blood, redblack on black. "Promethium," Jakob breathed. The miners crowded around him, faces lifted to it. Solly had a little pug nose, and squinched his face terribly in the effort to focus. Hester had a face to go with her voice, stark bones under skin scored with lines. "The most precious element. On Earth our masters rule by it. All their civilization is based on it, on the movement inside it, electrons escaping their shells and crashing into neutrons, giving off heat and more blue as well. So they condemn us to a life of pulling it out of the moon for them."

  He chipped at the chunk with a thumbnail. They all knew precisely its clayey texture, its heaviness, the dull silvery gray of it, which pulsed green under some lasers, blue under others. Jakob gave each of them a sliver of it. "Take it between two molars and crush hard. Then swallow."

  "It's poison, isn't it?" said Solly.

  "After years and years." The big laugh, filling the black. "We don't have years and years, you know that. And in the short run it helps your vision in the black. It strengthens the will."

  Oliver put the soft heavy sliver between his teeth, chomped down, felt the metallic jolt, swallowed. It throbbed in him. He could see the others' faces, the mesh of the pen walls, the pens farther down the concourse, the robot tracks—all in the lightless black.

  "Promethium is the moon's living substance," Jakob said quietly. "We walk in the nerves of the moon, tearing them out under the lash of the foremen. The shafts are a map of where the neurons used to be. As they drag the moon's mind out by its roots, to take it back to Earth and use it for their own enrichment, the lunar consciousness fills us and we become its mind ourselves, to save it from extinction."

  They joined hands: Solly, Hester, Jakob and Oliver. The surge of energy passed through them, leaving a sweet afterglow.

  Then they lay down on their rock bed, and Jakob told them tales of his home, of the Pacific dockyards, of the cliffs and wind and waves, and the way the sun's light lay on it all. Of the jazz in the bars, and how trumpet and clarinet could cross each other. "How do you remember?" Solly asked plaintively. "They turned me blank."

  Jakob laughed hard. "I fell on my mother's knitting needles when I was a boy, and one went right up my nose. Chopped the hippocampus in two. So all my life my brain has been storing what memories it can somewhere else. They burned a dead part of me, and left the living memory intact."

  "Did it hurt?" Hester croaked.

  "The needles? You bet. A flash like the foremen's prods, right there in the center of me. I suppose the moon feels the same pain, when we mine her. But I'm grateful now, because it opened my third eye right at that moment. Ever since then I've seen with it. And down here, without our third eye it's nothing but the black."

  Oliver nodded, remembering.

  "And something out there," croaked Hester.

  Next shift start Oliver was keyed by a foreman, then made his way through the dark to the end of the long, slender vein of blue he was working. Oliver was a tall youth, and some of the shaft was low; no time had been wasted smoothing out the vein's irregular shape. He had to crawl between the narrow tracks bolted to the rocky uneven floor, scraping through some gaps as if working through a great twisted intestine.

  At the shaft head he turned on the robot, a long low-slung metal box on wheels. He activated the laser drill, which faintly lit the exposed surface of the blue, blinding him for some time. When he regained a certain visual equilibrium—mostly by ignoring the weird illumination of the drill beam—he typed instructions into the robot, and went to work drilling into the face, then guiding the robot's scoop and hoist to the broken pieces of blue. When the big chunks were in the ore cars behind the robot, he jackhammered loose any fragments of the ore that adhered to the basalt walls, and added them to the cars before sending them off.

  This vein was tapering down, becoming a mere tendril in the lunar body, and there was less and less room to work in. Soon the robot would be too big for the shaft, and they would have to bore through basalt; they would follow the tendril to its very end, hoping for a bole or a fan.

  At first Oliver didn't much mind the shift's work. But IR-directed cameras on the robot surveyed him as well as the shaft face, and occasional shocks from its prod reminded him to keep hustling. And in the heat and bad air, as he grew ever more famished, it soon enough became the usual desperate, painful struggle to keep to the required pace.

  Time disappeared into that zone of endless agony that was the latter part of a shift. Then he heard the distant klaxon of shift's end, echoing down the shaft like a cry in a dream. He turned the key in the robot and was plunged into noiseless black, the pure absolute of Nonbeing. Too tired to try opening his third eye, Oliver started back up the shaft by feel, following the last ore car of the shift. It rolled quickly ahead of him and was gone.

  In the new silence distant mechanical noises were like creaks in the rock. He measured out the shift's work, having marked its beginning on the shaft floor: eighty-nine lengths of his body. Average.

  It took a long time to get back to the junction with the shaft above his. Here there was a confluence of veins and the room opened out, into an odd chamber some seven feet high, but wider than Oliver could determine in every direction. When he snapped his fingers there was no rebound at all. The usual light at the far end of the low chamber was absent. Feeling sandwiched between two endless rough planes of rock, Oliver experienced a sudden claustrophobia; there was a whole world overhead, he was buried alive…. He crouched and every few steps tapped one rail with his ankle, navigating blindly, a hand held forward to discover any dips in the ceiling.

  He was somewhere in the middle of this spa
ce when he heard a noise behind him. He froze. Air pushed at his face. It was completely dark, completely silent. The noise squeaked behind him again: a sound like a fingernail, brushed along the banded metal of piano wire. It ran right up his spine, and he felt the hair on his forearms pull away from the dried sweat and stick straight out. He was holding his breath. Very slow footsteps were placed softly behind him, perhaps forty feet away… an airy snuffle, like a big nostril sniffing. For the footsteps to be so spaced out it would have to be….

  Oliver loosened his joints, held one arm out and the other forward, tiptoed away from the rail, at right angles to it, for twelve feathery steps. In the lunar gravity he felt he might even float. Then he sank to his knees, breathed through his nose as slowly as he could stand to. His heart knocked at the back of his throat, he was sure it was louder than his breath by far. Over that noise and the roar of blood in his ears he concentrated his hearing to the utmost pitch. Now he could hear the faint sounds of ore cars and perhaps miners and foremen, far down the tunnel that led from the far side of this chamber back to the pens. Even as faint as they were, they obscured further his chances of hearing whatever it was in the cavern with him.

  The footsteps had stopped. Then came another metallic scrick over the rail, heard against a light sniff. Oliver cowered, held his arms hard against his sides, knowing he smelled of sweat and fear. Far down the distant shaft a foreman spoke sharply. If he could reach that voice…. He resisted the urge to run for it, feeling sure somehow that whatever was in there with him was fast.

  Another scrick. Oliver cringed, trying to reduce his echo profile. There was a chip of rock under his hand. He fingered it, hand shaking. His forehead throbbed and he understood it was his third eye, straining to pierce the black silence and see….

  A shape with pillar-thick legs, all in blocks of redblack. It was some sort of….

  Scrick. Sniff. It was turning his way. A flick of the wrist, the chip of rock skittered, hitting ceiling and then floor, back in the direction he had come from.

  Very slow soft footsteps, as if the legs were somehow… they were coming in his direction.

  He straightened and reached above him, hands scrabbling over the rough basalt. He felt a deep groove in the rock, and next to it a vertical hole. He jammed a hand in the hole, made a fist; put the fingers of the other hand along the side of the groove, and pulled himself up. The toes of his boot fit the groove, and he flattened up against the ceiling. In the lunar gravity he could stay there forever. Holding his breath.

  Step… step… snuffle, fairly near the floor, which had given him the idea for this move. He couldn't turn to look. He felt something scrape the hip pocket of his pants and thought he was dead, but fear kept him frozen; and the sounds moved off into the distance of the vast chamber, without a pause.

  He dropped to the ground and bolted doubled over for the far tunnel, which loomed before him redblack in the black, exuding air and faint noise. He plunged right in it, feeling one wall nick a knuckle. He took the sharp right he knew was there and threw himself down to the intersection of floor and wall. Footsteps padded by him, apparently running on the rails.

  When he couldn't hold his breath any longer he breathed. Three or four minutes passed and he couldn't bear to stay still. He hurried to the intersection, turned left and slunk to the bullpen. At the checkpoint the monitor's horn squawked and a foreman blasted him with a searchlight, pawed him roughly. "Hey!" The foreman held a big chunk of blue, taken from Oliver's hip pocket. What was this?

  "Sorry boss," Oliver said jerkily, trying to see it properly, remembering the thing brushing him as it passed under. "Must've fallen in." He ignored the foreman's curse and blow, and fell into the pen tearful with the pain of the light, with relief at being back among the others. Every muscle in him was shaking.

  But Hester never came back from that shift.

  Sometime later the foremen came back into their bullpen, wielding the lights and the prods to line them up against one mesh wall. Through pinprick pupils Oliver saw just the grossest slabs of shapes, all grainy black-and-gray: Jakob was a big stout man, with a short black beard under the shaved head, and eyes that popped out, glittering even in Oliver's silhouette world.

  "Miners are disappearing from your pen," the foreman said, in the miners' language. His voice was like the quartz they tunneled through occasionally: hard, and sparkly with cracks and stresses, as if it might break at any moment into a laugh or a scream.

  No one answered.

  Finally Jakob said, "We know."

  The foreman stood before him. "They started disappearing when you arrived."

  Jakob shrugged. "Not what I hear."

  The foreman's searchlight was right on Jakob's face, which stood out brilliantly, as if two of the searchlights were pointed at each other. Oliver's third eye suddenly opened and gave the face substance: brown skin, heavy brows, scarred scalp. Not at all the white cutout blazing from the black shadows. "You'd better be careful, miner."

  Loudly enough to be heard from neighboring pens, Jakob said, "Not my fault if something out there is eating us, boss."

  The foreman struck him. Lights bounced and they all dropped to the floor for protection, presenting their backs to the boots. Rain of blows, pain of blows. Still, several pens had to have heard him.

  Foremen gone. White blindness returned to black blindness, to the death velvet of their pure darkness. For a long time they lay in their own private worlds, hugging the warm rock of the floor, feeling the bruises blush. Then Jakob crawled around and squatted by each of them, placing his hands on their foreheads. "Oh yeah," he would say. "You're okay. Wake up now. Look around you." And in the after-black they stretched and stretched, quivering like dogs on a scent. The bulks in the black, the shapes they made as they moved and groaned… yes, it came to Oliver again, and he rubbed his face and looked around, eyes shut to help him see. "I ran into it on the way back in," he said.

  They all went still. He told them what had happened. "The blue in your pocket?"

  They considered his story in silence. No one understood it.

  No one spoke of Hester. Oliver found he couldn't. She had been his friend. To live without that gaunt crow's voice….

  Sometime later the side door slid up, and they hurried into the barn to eat. The chickens squawked as they took the eggs, the cows mooed as they milked them. The stove plates turned the slightest bit luminous—redblack, again—and by their light his three eyes saw all. Solly cracked and fried eggs. Oliver went to work on his vats of cheese, pulled out a round of it that was ready. Jakob sat at the rear of one cow and laughed as it turned to butt his knee. Splish splish! Splish splish! When he was done he picked up the cow and put it down in front of its hay, where it chomped happily. Animal stink of them all, the many fine smells of food cutting through it. Jakob laughed at his cow, which butted his knee again as if objecting to the ridicule. "Little pig of a cow, little piglet. Mexican cows. They bred for this size, you know. On Earth the ordinary cow is as tall as Oliver, and about as big as this whole pen."

  They laughed at the idea, not believing him. The buzzer cut them off, and the meal was over. Back into their pen, to lay their bodies down.

  Still no talk of Hester, and Oliver found his skin crawling again as he recalled his encounter with whatever it was that sniffed through the mines. Jakob came over and asked him about it, sounding puzzled. Then he handed Oliver a rock. "Imagine this is a perfect sphere, like a baseball."

  "Baseball?"

  "Like a ball bearing, perfectly round and smooth you know."

  Ah yes. Spherical geometry again. Trigonometry too. Oliver groaned, resisting the work. Then Jakob got him interested despite himself, in the intricacy of it all, the way it all fell together in a complex but comprehensible pattern. Sine and cosine, so clear! And the clearer it got the more he could see: the mesh of the bullpen, the network of shafts and tunnels and caverns piercing the jumbled fabric of the moon's body… all clear lines of redblack on black, like the m
etal of the stove plate as it just came visible, and all from Jakob's clear, patiently fingered, perfectly balanced equations. He could see through rock.

  "Good work," Jakob said when Oliver got tired. They lay there among the others, shifting around to find hollows for their hips.

  Silence of the off-shift. Muffled clanks downshaft, floor trembling at a detonation miles of rock away; ears popped as air smashed into the dead end of their tunnel, compressed to something nearly liquid for just an instant. Must have been a Boesman. Ringing silence again.

  "So what is it, Jakob?" Solly asked when they could hear each other again.

  "It's an element," Jakob said sleepily. "A strange kind of element, nothing else like it. Promethium. Number 61 on the periodic table. A rare earth, a lanthanide, an inner transition metal. We're finding it in veins of an ore called monazite, and in pure grains and nuggets scattered in the ore."

  Impatient, almost pleading: "But what makes it so special?"

  For a long time Jakob didn't answer. They could hear him thinking. Then he said, "Atoms have a nucleus, made of protons and neutrons bound together. Around this nucleus shells of electrons spin, and each shell is either full or trying to get full, to balance with the number of protons—to balance the positive and negative charges. An atom is like a human heart, you see.

  "Now promethium is radioactive, which means it's out of balance, and parts of it are breaking free. But promethium never reaches its balance, because it radiates in a manner that increases its instability rather than the reverse. Promethium atoms release energy in the form of positrons, flying free when neutrons are hit by electrons. But during that impact more neutrons appear in the nucleus. Seems they're coming from nowhere. So each atom of the blue is a power loop in itself, giving off energy perpetually. Some people say that they're little white holes, every single atom of them. Burning forever at nine hundred and forty curies per gram. Bringing energy into our universe from somewhere else. Little gateways."