“Let’s pay it,” Hari said.

 “I wonder if it will provide a tracer for Lamurk?” Dors said over the internal comm.

 “What is our option?”

 “I shall use my own personal indices.”

 “For a wormhole transit? That will bankrupt you!”

 “It is safer.”

 Hari fumed while they floated in magnetic grapplers beneath the Imperial picket ship. The wormhole orbited a heavily industrialized world. Gray cities sprawled over the continents and webbed across the seas in huge hexagonals.

 The Empire had two planetary modes: rural and urban. Helicon was a farm world, socially stable because of its time-honored lin­ eages and stable economic modes. Such worlds, and the similar Femorustics, lasted.

 Obejeeon, on the other hand, seemed to cater to the other basic human impulse: clumping, seeking the rub of one’s fellows. Trantor was the pinnacle of city clustering.

 Hari had always thought it odd that humanity broke so easily into two modes. Now, though, his pan experience clarified these proclivities.

 Pan love of the open and natural had its parallel in the rustic worlds. This included a host of possible societies, especially the Femo-pastoral attractor in psychohistory-space.

 Its opposite pole—claustrophobic, though reassuring societ-ies—emerged from the same psychodynamic roots as the pans’ tribal gathering. Pans’ obsessive grooming expressed itself in humans as gossip and partying. Pan hierarchies gave the basic shape to the various Feudalist attractor groups: Macho, Socialist, Paternal. Even the odd thantocracies, of some of the Fallen Worlds, fit the pattern. They had Pharaoh-figures promising admission to an afterlife and detailed rankings descending from his exalted peak in the rigid social pyramid.

 These categories he now felt in his gut. That was the element he had been missing. Now he could include nuances and shadings in the psychohistorical equations which reflected earned experience. That would be much better than the dry abstractions which had led him so far.

 “They’re paid off,” Dors sent over the comm. “Such corruption!”

 “Ummm, yes, shocking.” Was he getting cynical? He wanted to turn and speak with her, but their pencil ship allowed scant social­ izing.

 “Let’s go.”

 “Where to?”

 “To…” He realized that he had no idea.

 “We have probably eluded pursuit.” Dors’ voice came through

 stiff and tight. He had learned to recognize signs of her own tension.

 “I’d like to see Helicon again.”

 “They would expect that.”

 He felt a stab of disappointment. Until now he had not realized how close to his heart his early years still were. Had Trantor dulled him to his own emotions? “Where, then?”

 “I took advantage of this pause to alert a friend, by wormlink,” she said. “We may be able to return to Trantor, though through a devious route.”

 “Trantor! Lamurk—”

 “May not expect such audacity.”

 “Which recommends the idea.”

 7.

 It was dizzying—leaping about the entire galaxy, trapped in a casket-sized container.

 They jumped and dodged and jumped again. At several more wormhole yards Dors made “deals.” Payoffs, actually. She deftly dealt combinations of his cygnets, the Imperial Passage indices, and her private numbers.

 “Costly,” Hari fretted. “How will I ever pay—”

 “The dead do not worry about debts,” she said.

 “You have such an engaging way of putting matters.”

 “Subtlety is wasted here.”

 They emerged from one jump in close orbit about a sublimely tortured star. Streamers lush with light raced by them.

 “How long can this worm last here?” he wondered.

 “It will be rescued, I’m sure. Imagine the chaos in the system if a worm mouth begins to gush hot plasma.”

 Hari knew the wormhole system, though discovered in pre-Empire ages, had not always been used. After the underlying physics of the wormhole calculus came to be known, ships could ply the Galaxy by invoking wormhole states around themselves. This af­ forded exploration of reaches devoid of wormholes, but at high energy costs and some danger. Further, such ship-local hyperdrives were far slower than simply slipping through a worm.

 And if the Empire eroded? Lost the worm network? Would the slim attack fighters and snakelike weapons fleets give way to lum­ bering hypership dreadnoughts?

 The next destination swam amid an eerie black void, far out in the halo of red dwarfs above the Galactic plane. The disk stretched in luminous splendor. Hari remembered holding a coin and thinking of how a mere speck on it stood for a vast volume, like a large Zone. Here such human terms seemed pointless. The Galaxy was one serene symphony of mass and time, grander than any human perspective or pan-shaped vision.

 “Ravishing,” Dors said.

 “See Andromeda? It looks nearly as close.”

 The twin spiral hung above them. Its lanes of clotted dust framed stars azure and crimson and emerald. “Here comes our connection,” Hari warned.

 This wormhole intersection afforded five branches. Three black spheres orbited closely together, blaring bright by their quantum rim radiation. Two cubic wormholes circled farther out. Hari knew that one of the rare variant forms was cubical, but he had never seen any. Two together suggested that they were born at the edge of galaxies, but such matters were beyond his shaky understanding.

 “We go—there.” Dors pointed a laser beam at one of the cubes, guiding the pencil ship.

 They thrust toward the smaller cube, gingerly inching up. The wormyard here was automatic and no one hailed them.

 “Tight fit,” Hari said nervously.

 “Five fingers to spare.”

 He thought she was joking, then realized that she was underes­ timating the fit. At this less-used wormhole intersection slow speeds were essential. Good physics; unfortunate economics. The slow­ down cut the net flux of mass, making them backwater crossroads.

 He gazed at Andromeda to take his mind off the piloting. Narrow wormholes did not emerge in other galaxies for arcane reasons of quantum gravity. Extremely narrow ones might, but if the throat had other mass coming through, the squeeze wave could kill. Few had ever ventured down them in search of extragalactic emergent points.

 Except, that is, for Steffno’s Ride, a legendary risky expedition which had popped out in the galaxy cataloged as M87. Steffno had gotten data on the spectacular jet emerging from the black hole at M87’s center, majestic strands twisting into helical arabesques. The lone rider had not tarried, returning only seconds before the worm snapped shut in a spray of radiant particles.

 No one knew why. Something in wormhole physics discouraged extragalactic adventures.

 The cubic worm took them quickly to several wormyards in close orbit about planets. One Hari recognized as a rare type with an old but ruined biosphere. Like Panucopia, it supported advanced life-forms. On most inhabitable worlds early explorers had found algae mats that never developed further.

 “Why no interesting aliens, then?” Hari mused while Dors dealt with the local wormyard Grey Men.

 Occasionally Dors reminded him that she was, after all, an his­ torian. “The shift from one-celled to many-celled creatures took billions of years, theory says. We just came from a fast, tougher biosphere, that’s all.”

 “We came from a planet with at least one big moon, too.”

 “Why?” she asked.

 “We’ve got repeating patterns of twenty-eight days built in. Fe­ male menstruation, for instance—unlike pans, incidentally. We’re designed by biology. We made it, these biospheres didn’t. There are plenty of ways to kill a world. Glaciers advancing when an orbit alters. Asteroids slamming in, bam-bam-bam!” He slapped the side of the pencil ship loudly. “Chemistry of the atmosphere goes wrong. It runs away into a hothouse planet, or a frozen-out world.”

 “I see.”

 “Humans are tougher—and smarter—than anybody. We’re here, they aren’t.”

 “Who says?”

 “Standard knowledge, ever since the sociotheorist, Kampfbel—”

 “I’m sure you’re right,” she said quickly.

 Something in her voice made him hesitate—he loved a good ar-gument—but by then they were slipping through the excruciating tight fit of the cube. The edges glowed like a lemony Euclidean construction—and then they popped into an orbit above a black hole.

 He watched the enormous energy-harvesting disks glow with fermenting scarlets and virulent purples. The Empire had stationed great conduits of magnetic field around the hole. These sucked and drew in interstellar dust clouds. The dark cyclones narrowed toward the brilliant accretion disk around the hole. Radiation from the friction and infalling was in turn captured by vast grids and reflect­ ors. The crop of raw photon energy itself became trapped and flushed into the waiting maws of wormholes. These carried the flux to distant worlds in need of cutting lances of light, for the business of planet-shaping, world-raking, moon-carving.

 But even amid this spectacle he could not forget the tone in Dors’ voice. She knew something he did not. He wondered…

 Nature, some philosophers held, was itself only before humanity touched it. We did not then belong in the very idea of Nature, and so we could experience it only as it was disappearing. Our presence alone was enough to make Nature into something else, a comprom­ ised impersonation.

 These ideas had unexpected implications. One world named Arcadia had been deliberately left with a mere caretaker population of humans, partly because it was difficult to reach. The nearest wormhole mouth was half a light-year away. An early emperor—so obscure his or her very name was lost—had decreed that the forests and plains of the benign planet be left “original.” But ten thousand years later, a recent report announced, some forests were not regenerating, and plains were giving way to scrubby brush.

 Study showed that the caretakers had taken too much care. They had put out wild fires, suppressed species transfer. They had even held the weather nearly constant through adjustments in how much sunlight the ice poles reflected back into space.

 They had tried to hold onto a static Arcadia, so the forest primeval was revealed as, in part, a human product. They had not understood cycles. He wondered how such an insight might fold into psychohistory….

 Forget theory for the moment, he reminded himself. It was a fact that the Galaxy had seemed empty of high alien life-forms in the early, pre-Empire times. With so many fertile planets, did he truly believe that only humanity had emerged into intelligence?

 Somehow, surveying the incomprehensible wealth of this lush, immense disk of stars…somehow, Hari could not believe it.

 But what was the alternative?

 8.

 The Empire’s twenty-five million worlds supported an average of only four billion people per planet. Trantor had forty billion. A mere thousand light years from Galactic Center, it had seventeen wormhole mouths orbiting within its solar system—the highest density in the Galaxy. The Trantorian system had originally held only two, but a gargantuan technology of brute interstellar flight had tugged the rest there to make the nexus.

 Each of the seventeen spawned occasional wild worms. One of these was Dors’ target.

 But to reach it, they had to venture where few did.

 “The Galactic Center is dangerous,” Dors said as they coasted toward the decisive wormhole mouth. They curved above a barren mining planet. “But necessary.”

 “Trantor worries me more—” The jump cut him off—

 —and the spectacle silenced him.

 The filaments were so large the eye could not take them in. They stretched fore and aft, shot through with immense luminous cor­ ridors and dusky lanes. These arches yawned over tens of light-years. Immense curves descended toward the white-hot True Center. There matter frothed and fumed and burst into dazzling fountains.

 “The black hole,” he said simply.