How odd. The machine hadn’t noticed that cubbyhole. Opening it with a touch, he is surprised and amazed and a little scared to find a small bottle filled with a grayish substance that has no weight whatsoever.

“Empty it into me,” Pamir says.

The shopkeeper complies immediately. An unknown quantity of raw data is absorbed by the tall bundle of shaped light.

“Now put it back again, please.”

The bottle records nothing but the opinions expressed by the shopkeeper. Passersby are not recalled—not their faces or voices, much less their names. The AI is a mirror, of sorts. He is a template. To make a sale, he will put on any face or attitude, and both are cues to slippery moods of its clients.

“Thank you,” says the projection.

“You are welcome, I suppose. Sir.”

Together, they walk outside again.

“Perhaps I should ask—” the machine begins.

“You wouldn’t remember, even if I told you.”

Somehow, that seems like enough of an answer. The shopkeeper nods and looks down at the human shoes that he wears at this moment, glassy eyes watching the cool pure water slipping down into the passing river.

“How long have you had this shop?” the projection inquires.

“Since the first thousand years of the voyage, nearly.”

“And you drain this reservoir how often?”

“Every eleven days, ship-time.”

“But the stone isn’t worn, ” the rumbling low voice points out. “You see? If you’d been here for a thousand centuries, and if every eleven days you drained this one reservoir, not to mention your other stockpiles …”

“I do not understand” the machine confesses.

But he is alone suddenly and what he doesn’t understand is why he is speaking to himself.

The little river flows to the end of the avenue, dives through another long conduit, and after being heated to the brink of boiling, the water is shoved up into a mass of black mud and dirty bubbles of methane. Inside a diamond bubble, a thousand creatures sit in the soft scalding mud. For the last twenty thousand years, this is where they have lived. Every need flows to them. Every curiosity is answered by nexuses and glow-screens and other standard tools. Their species has no common name, just a set of numbers and letters designated by the captains who admitted them to the Great Ship. They are intensely social creatures, but only with their own kind. Paradise is a hot wet realm full of stink and sudden fires and the musical roar of farts, great voices rising up through the steam, telling one another. “This herd did not pay for the wrong path. Steer toward our destination, as promised, or we demand our fees returned in full … !”

The water is cleaned again and set free again, merging with another little river before a long, spiraling fall through a series of fresh caverns and long avenues. Each chamber differs in the native rock and the steepness of the slope, in its width and height and how the terrain has been shaped. Billions of years ago, unknown hands worked with rock and hyperfiber, fractals and the demands of engineering, contriving clifflike walls and granite shoulders and mock-faults and too many side caverns to count. Even ceilings refuse to be predictable: Hyper-fiber forms ribs or fat arches or interwoven domes, and, depending on the grade, they are as bright as mirrors or gray as cold smoke. Or there are stone ceilings braced with little spines of hyperfiber—pink granites or black basalts or bright green olivines, or cultured ruby or diamond or sapphires, singly or mixed into an elaborate but seemingly accidental stew of glittering faces. There are no artificial skies. The only lights are small and occasional, and simple, casting a feeble white glow over the river’s busy face. There is no soil on the shoreline and no intentional life anywhere. For the moment, this drainage is being held in reserve. Much of my interior is the same. For all the billions of passengers, there is little need to open up most of my emptiness. After more than a hundred thousand years, I remain mostly wilderness, a realm of untouched stone and empty spaces hovering on the brinks of Time.

The river steals up minerals from the surrounding stone, feeding a few patient microbes, while some presentient machines turn parasitic, milking power from the occasional light. Sometimes tourists wander in here and out again, leaving behind intense little colonies of life on their wastes and discarded meals. A tuft of gray-green marks a rotting sandwich. A bluish smear is all that remains of an enormous fecal pile. Then there is the tourist who never left—a biped of some obscure species who wandered into this cavern alone, scaled the enormous clifflike wall, and at the worst possible moment lost his grip on his inadequate rope. The fall shattered both of his legs and both of his spines. The essential equipment that he carried with him was left high above, out of reach. Immortal but lacking a human’s relentless repair mechanisms, he had no choice but to remain where he lay Then starvation and thirst drove him into a deep coma, and what survives today sits in a little bowl just three meters above the waterline—a mummified body that has not moved in the last eighteen centuries.

The river meets a new river and little springs, twisting and curling and always falling as it swells into a deep, swift, and relentless torrent. Fifty thousand kilometers have been covered, with a drop of better than two thousand. The last empty cavern is vast, a wide flat floor allowing the water to wander like a fat snake between walls that to the casual eye look like barren mountains. Brown rock and gray rock camouflage what covers a portion of one wall. Homes and glass domes hide on that steep terrain. For twenty kilometers, a secret city thrives. This is an unlisted community The captains know about it, but, except where security has leaked, nobody else is aware of its existence. Almost since the beginning of the voyage, humans have lived on this stark ground. They are luddites of a certain odd order. For reasons religious as well as reasoned, they don’t believe in many of the modern technologies. Life should be mortal and brief, since there is a golden afterlife, and why would anyone wish to avoid such a glorious fate? Old age begins before their second century but death can come any moment. They wear out-of-date costumes and odd hairstyles, and each carries one of three sacred texts at all times. They are isolationists. Only on special occasions do they trade with the rest of the passengers, and only through distant intermediaries. They don’t believe in nexuses or glow-screens. But they approve of fusion power and intensive agriculture, and every home has a decent library, and despite their brief life span, much emphasis is placed on learning and all of the great questions that are older than their species.

Two old men stand at the base of their brown mountains, holding hands as friends should, watching the fishless river slide past their boots.

“If the captains cannot turn the ship,” one man mentions, “then it will continue out into the cold between the galaxies.”

“As I hear it,” his friend concurs.

“In another few thousand years,” the first man adds.

“As they say.”

“And then after another long while, the Virgo cluster is achieved.”

The distances and spans of time are enormous, almost too much to imagine. But the second man tries his best before allowing, “If it is God’s plan.”

“Unless it is not,” his friend says ominously.

But they are old men, each to die in another little while, and because they are mortal and brief, they feel blessed: Not even their children’s children will have to deal with such terrible questions.