“Ah — look at that.” Reath pointed to the horizon, where a column of darkness, writhing visibly, connected the ocean to the sky. “Do you know what that is?”

“Is it weather?”

“Alia, that is a hurricane. A kind of storm, a vortex of air. It is fueled by heat from the upper levels of the sea. It twists and moves, you see — chaotically, but not unpredictably.”

“It is a phenomenon of a water-world.”

“Not just world-oceans. Any planet with extensive seas and a respectable atmosphere can spawn such twisters. Even Earth! If there is land, of course, the storm can track away from the sea.”

Alia had grown up in a bubble of air less than two kilometers wide, every molecule of which was climate-controlled and cleansed by the Nord’s antique, patient machines. She tried to imagine such a monstrous storm slamming into a town or a city on Earth. Her imagination was unformed, filled with images of catastrophic breakdowns of environment control systems. “How terrible,” she said.

“Oh, humans mastered hurricanes long ago. All you have to do is cut off their energy supply before they do any damage. And of course by tracking on to land they detach themselves from the ocean that feeds them, and die of their own accord.”

“But not here, for there is no land.”

“Not here, no. Here a twister can live on and on, sucking up energy, spinning off daughters, tracking around the world. One twister system here — I’m not sure if it is that one — reaches right up to the top of the atmosphere. You can see it from space, like a glowering eye. And it has persisted for thousands of years.”

This was terribly disturbing for a ship-born girl like Alia. She was relieved when the storm receded from sight behind the horizon.

It was a month since she had agreed to follow Reath, to leave her home and begin the program of training that might, ultimately, remarkably, lead to her becoming that unknowable entity — a Transcendent, to become one of the host of godlike post-humans who governed mankind. A month since she had placed herself in the care of an agent of the Commonwealth.

The Commonwealth! Before she had left the Nord it had been little more than a name to her, a shadowy authority that arched over human civilization, as lofty and remote and beautiful as an interstellar cloud, and as irrelevant. Now she was beginning to get a sense of the reality of it — and it was much more than she had ever imagined.

The Commonwealth was based at the most logical place for a Galactic capital: on a cluster of worlds that drifted amid the millions of crowded suns of the Core, where mankind had always anchored its Galactic empires.

The most visible sign of the Commonwealth’s presence was the Clock of Humanity. Lodged in the Core, this was a machine the size of the star. It used the decay of certain types of subatomic particles, called W and Z bosons, to produce pulses of neutrinos. These were the fastest known physical processes; no conceivable clock could be more precise. And as neutrinos passed like ghosts through all normal forms of matter, the pulses washed through the stars and dust of the Galaxy and never occluded or dispersed, so you could pick up the clock’s chiming wherever you were. Once, it was said, human clocks had been devised to fit the natural rhythms of Earth, its days and years. Now humans had scattered over millions of disparate worlds, and so the Clock was calibrated to a standard human pulse rate. Thus a civilization that encompassed a Galaxy marched in step to the rhythms of a human heart.

“And all of it,” Reath told her, “is driven by the Transcendence — a Commonwealth within the Commonwealth, a center within the center, the innermost heart of everything.”

The Transcendence was the source of all authority. As far as she could make out, it was itself a meshing of minds, a titanic superhuman mass around which human affairs pivoted, much as the Galaxy itself wheeled about the unmovable black hole at its very center. But the Transcendence needed agencies to carry out its will in the human world: it was a god embedded in bureaucracy.

The Commonwealth was more than a collection of dusty agencies, though, Reath said. The Commonwealth itself was an aspiration. As it worked on a Galactic scale, bit by bit, humans were drawn closer together, knit more integrally into the whole. Reath liked to say that whether you knew about it or not, if you were of human descent you were a citizen of the Commonwealth already. “And one day, it is hoped,” Reath said, “we will all be drawn in, not just into the Commonwealth, but even into the Transcendence itself — and then a new kind of human history will begin.”

But if it was to achieve such aspirations, the Transcendence had to grow. It had to recruit. Astonishing as it seemed, the Transcendence needed people like Alia.

If her ultimate goal was barely imaginable, Reath reassured her, the training would come in easy chunks. There were three formal stages, which he called Implications: the Implication of Indefinite Longevity, of Unmediated Communication, and of Emergent Consciousness. Needless to say she had little idea what any of these terms might actually mean, though they all sounded scary. But as well as the formal steps they would enjoy some “fun” together, Reath said: notably, travel to exotic worlds like this one.

She wasn’t happy.

It wasn’t the distances that troubled her. To a Skimmer, distance was supposed to be meaningless anyhow. No, it wasn’t the distance but the company she had to keep: her only companion, in his austere, joyless tube of a ship was the silent and watchful Reath.

Reath wasn’t bad company, really. He was attentive to her needs, and tolerated her moods, and much of what he had to say was even interesting. But his face was blank, expressionless, as immobile as if the nerve ends had been cut. He was a walking, talking emblem of the great severance she had undergone, her separation from the Nord, her whole world, and her rejection by her parents in favor of a baby brother she did her level best not to hate.

Reath had done her one great favor, though. He had allowed her to bring along her Witnessing tank.

She could watch Michael Poole any way she pleased. The basic wormlike chain of images, from Poole’s birth to death, was a simple four-dimensional representation, an index. She could allow a scene from his life to unfold inside the tank, with Poole, his family and friends, enemies and strangers, like tiny actors. Or she could magnify it and immerse herself in the scene, an unseen witness.

All of this was utterly authentic, so she understood, though she knew nothing of the technology involved: this wasn’t a reconstruction, this really was the life of Michael Poole as he had lived it, five thousand centuries ago, all of it from birth to death embedded deep in the irrevocable past, and locked up inside her tank for her benefit.

Reath reminded her it was the obligation of every citizen to keep up her program of Witnessing, as ordained by mysterious bodies at the heart of the Commonwealth, which he called “the Colleges of Redemption.” So he allowed her to believe she wasn’t after all being helplessly sentimental in clinging to Michael Poole, her childhood companion; it was her duty. Perhaps he was sparing her feelings, and if so she was grateful for his indulgence. But he did take the Witnessing very seriously indeed, for he said the Redemption was at the heart of the greatest ambitions of the Transcendence.

And so, in the bowels of Reath’s severe ship, as the stars sailed by, she spent long hours immersed in the bright Florida light of Poole’s long-ago childhood. She wished she could be there now, gazing not on this dismal water-world but on the sparkling seas of Earth.

Hundreds of kilometers of featureless ocean passed under the flitter’s prow.