“Then you must have been educated above the work of guard duty for a boy.”

“It doesn’t make a soldier worse to have an education.”

“It makes it harder for him to take orders from idiots,” said Rigg.

“Well, that’s true,” said Ovilenko. “Which is why I’m a man of no rank.”

Rigg was about to ask him to sit with him at a table and tell him all about his father, but at that moment Bleht arrived, and Rigg had no choice but to return to his original mission.

The microbiologist looked suspicious and annoyed. Whatever she had been doing when summoned, she was not glad of the interruption. Rigg apologized briefly but then got straight to his point.

“I believe that my father Knosso did not discover a great secret of physics before he made his attempt to float through the Wall out at sea.”

“Unless you think it was a great secret of microbiology, I fail to see what I can contribute to your speculations.”

“I think my father started pursuing a completely different line of research.”

“A microbial one?”

“Historical,” said Rigg. “More particularly calendrical. I think he read your paper on the duality of the flora and fauna of the wallfold. Two separate origins of life in the wallfold. I think he wrote to you or sent word to you, and you went to the Library of Past Lives several times to meet with him.” Actually, Rigg knew it to be a fact, having seen the intersection of their paths, but until now he had thought it meant something completely different.

Bleht sat down and patted the seat beside her. “Now I recognize your friend here,” she said, then turned to Ovilenko, looking grimly amused. “You were his clerk, weren’t you. A lot shorter then.”

“Young citizen Rigg had already asked to talk with you before I told him about that,” said Ovilenko stiffly.

“But that doesn’t mean that he didn’t already know.”

“I didn’t, but what does it matter?” asked Rigg. “I want to know what you talked about.”

“The weather,” said Bleht.

“Yes,” said Rigg. “I believe you did talk about the weather. And the climate, and everything else, because you had looked back in time for your reasons, and he for his, and he wanted to compare what both of you had found.”

“If you’re so clever,” said Bleht, “what did your father find?”

“I’ll only know that when you tell me. Why do you think I already know?”

“I think you have a good idea or you wouldn’t have come to me. I think you know everything, and it amuses you to pretend to be young and naive.”

“I only noticed it by accident in the Library of Past Lives—a timeline of history. It was a large sheet of paper, or rather, a very wide one, folded small enough to fit within the covers of a book written by an ancient scholar of the Losse Dynasty. The timeline had been copied three times, judging by the number of copyists’ initials.”

She said nothing, which Rigg took to mean that she didn’t want to give him encouragement—and the less encouragement she wanted to give him, the more encouraged he felt that he might be on a productive track.

“This timeline starts in the year 11191.”

“Given our calendar, all timelines do,” said Bleht. “It doesn’t mean they aren’t fictional.”

“But there’s a marginal notation—signed by the maker of the timeline, and then faithfully reproduced by the copyists—that as near as he can find, by cross-checking all the known calendars, human history actually began eleven thousand years in our past—nearly two hundred years after the start of the calendar.”

“Dates for imaginary historical events are very hard to pin down sometimes,” said Bleht. But she wasn’t getting up and walking away, either.

“My father Knosso wanted to know if the Lossene timeline coincided with your understanding of the history of one of the streams of life.”

“What kind of calendar would a microbiologist be familiar with?”

“Something you didn’t say in your paper—”

“You read it? By yourself?”

“I moved my lips a little, and counted on my fingers,” said Rigg, which won a little bark of laughter from her. “What you didn’t say in your paper was that one of the streams of evolution—and by far the largest—did not appear in the wallfold until about eleven thousand years ago. We are in that group, genetically related to each other, to all the animals we kill to eat or tame to serve us, but resembling no strain of local life.”

“Local? Does that mean you think that our biochemical strain, the larger one, did not develop locally?”

“I don’t know what I mean or think,” said Rigg, though in fact he thought now that this was precisely what her paper was really about, though she dared not risk her scholarly reputation by saying so. “I want to know what you and my father Knosso talked about.”

“We talked about you,” said Bleht.

Rigg was taken aback. “Me?”

“You were still only an infant,” she said. “And then you were gone. Kidnapped, fallen down a well, whatever the Revolutionary Council pretended to discover in their investigation of your disappearance. We talked about what might have happened to you. Not some weird timeline sequestered in a Lossean-era textbook.”

“I don’t believe you,” said Rigg.

“Disbelieve what you like.”

“I think you had reason to believe that our biological tradition was not visible in archaeological digs prior to eleven thousand years ago. Your paper hints at this.”

“That was sheer entertainment—it was in the introduction, not serious science.”

“My father Knosso believed it. He combined the timeline and your discoveries and concluded that human beings and most of the animals in the world were introduced to our wallfold quite suddenly. We’re from somewhere else.”

“What? Seeds blown through the Wall?” she asked derisively. “All this evolution in eleven thousand years?”

“I don’t mean from another wallfold—plants and seeds propagate freely through the Wall. I mean from another world. Maybe another solar system.” And, as he said those words, it occurred to Rigg for the first time that maybe Father—not Knosso, but the man who died under a tree—had been hinting to him about the same idea. It had come so easily to his mind, and he realized now that Father had made it a point to teach him in detail about astronomy and the development of life over millions of generations, millions of years.

One idea in particular now came unbidden into his mind—no doubt embedded there by Father so it would surface at exactly this moment. Father had talked about the “tidal limit” and how, if the millions of rocks and chunks of ice making up the Ring had formed only a few thousand miles farther away, they would have coalesced to form a spherical moon. “A large enough moon would create tides in all the oceans of the world,” he had said. “Life would develop on such a world much faster than on ours, because on a moon-tide world the sea would sweep much farther across low-sloping shores. It’s in soils and pools of water where land and sea and air meet that life begins, and a world with a moon has far, far more of them.”

Had Father been telling him that it was his theory that human beings came from such a world? That life had advanced much faster on the original human world?

“That’s an astronomical and historical question,” Bleht said.

It took Rigg a moment to realize she was not reading his mind and answering his thoughts. Instead she was answering his statement about “maybe another solar system.”

“Don’t you see what this would mean to Father Knosso?” asked Rigg. “He was searching for a way over or through the Wall. He couldn’t find anything in physics or history, but he had found, through the timeline, through your work, the idea that maybe our calendar begins with the arrival of human beings, and all the life they brought with them, as strangers to this world.”

“So what?” asked Bleht.

“Were the Walls here when they arrived? How could any kind of life system evolve on a world where any creature with a higher brain function cannot pass from wallfold to wallfold? Neither the original strain of life nor the one our ancestors brought with them from their world-with-a-moon could have developed on a planet with Walls.”