Too often, she spoke about her work and its biggest problems.

When Locke stared off into the distance, watching a fat hammerwing flying against the illusionary sky, she would stop herself. In midsentence, if necessary. Then with a sorrowful honesty, she would say, “Sorry.”

At first, Locke would nod, and say, “No, it’s all right.”

Then Washen would insist, “I want to hear about your work. What are you doing now?”

But after a few decades of graceless niceties, her son decided simply to leap past her weak apology as well as the rest of the traditional noise. Washen would be recounting what she believed to be an interesting story, perhaps about an obscure species and how she had handled them in a dangerous moment … and in midsentence, Locke would blurt out, “My work is going well.”

It was his signal, and after a few more decades, Washen stopped feeling insulted or embarrassed.

“I’m still learning about the science and mathematics,” her son would explain. He had enjoyed a thorough education as a boy on Marrow, but those were harsh times, and on Marrow, children and their society had no clear picture of the greater universe. “I’ve still got a long way to go,” his confession went. “And that’s just until I can match what the AIs know by pure instinct. Doing any significant work … well, that might never happen. Who can say?”

“But you’re learning,” she would remind him.

Locke would nod and smile amiably, pleased to have his discipline recognized. Then he might tell his mother a long, convoluted story about some odd feature in one of the six essential Theories of All. In common usage, there was just the single Theory. Robust and remarkably simple, it seemed to explain everything of substance about the universe, from its tiny birth to its endless inflation, from the relatively quiet present and into the gathering darkness, with its bitter cold and the eventual, inevitable death. Only certain rarefied specialists bothered with the incongruities and wilder details: What was the basic nature of the superuniverse? Was time real or an illusion? Were the parallel existences genuine, or were they just mathematical conveniences? And was there anyplace inside this conundrum for something that might be labeled “the soul”?

Out of simple convenience, those detailed and often contrary theories had been lumped into six equal categories, or species, or little hills.

As the daughter of engineers, and then as the trained captain of a starship, Washen had been promised that each of those theories was as valid as any other, and just as trivial. There was no available means to test them against one another, at least not inside this universe. But their lofty and deeply clever mathematics always pointed to the same conclusion. Washen was traveling through an existence that was inevitable—a tail of reality riding on the end of every great equation. The only factor that mattered to a captain was which of her passengers believed in which of the six theories. Each had its attractions and inducements, as well as its disagreeable points. Most species embraced whatever vision of All would make them sleep easiest or live best or accept their own hard existences with the least complaint. What they believed was a window on their nature, and sometimes when Locke spoke about one of the theories, she would mention, in passing, “The Galloon don’t believe in time, either,” or with a tisk-tisking tone, she would warn Locke, “The harum-scarums despise the idea of parallel realities. There’s only one existence, and of course they have to be at the middle of it.”

Locke would nod patiently, perhaps showing a little grin. He didn’t particularly care about the aesthetics of any species, including his own. What he was striving for was to sit on a high point and look at the terrain without prejudice, seeing everything that there was to see.

During one of the little lunches, more than ten decades after the Wayward War, he launched into a description of a new mathematics. At first, Washen listened intently and felt certain that she understood the heart of it. But at some point during the monologue, she realized that she hadn’t any clue about what the sounds striking her ears could possibly mean. As always, Locke had given her files to examine—lessons and illustrations produced from his own notes and elaborate papers—and she linked herself to the day’s files, burrowing deep, then coming up again like a drowning woman bursting out of a cold bottomless sea.

“What are you talking about?” she blurted.

But her son had ceased talking, probably several minutes ago.

“I don’t understand any of this,” she confessed. Complained. And then with a self-deprecating laugh, she said, “Throw me a line, darling. Would you?”

“A line?” The image didn’t make immediate sense to him.

Finally, a dim old memory tickled her mind. Washen said, “Wait,” before her son could offer an explanation. “I remember now.”

“What?”

“My mother, and a few teachers … they would sometimes mention … what was it … ?” She closed her dark eyes, concentrating. “A seventh Theory of All. Very obscure, and trivial … nobody ever actually believes in it …”

Locke’s response was a gentle shrug and a nod.

“I don’t know anything about the seventh Theory,” she said again, begging for any help.

But Locke could only shrug, admitting, “I don’t know much more than you.” Then after a long pause, he added, “It is a disgusting set of equations. Really, even the AIs—my teachers, my colleagues—they despise that seventh solution to everything. It’s that ugly, that sad. If it wasn’t fascinating, I doubt if they’d ever look at it twice.”

THREE DECADES LATER, in the midst of another lunch, Washen again asked, “How are the lessons going?”

He smiled broadly, which was a little odd.

Then with a shrug of his shoulders, he mentioned, “I’m actually accomplishing a little work now. Nothing important. But at least I’m building a framework for everything that I’ll accomplish in the next million years.”

He meant it. When he spoke of such an enormous period of time, he did it with a pure and withering expertise. Better than almost anyone, Locke understood that frightening span of time. And with a devotion that only fanatics and madmen could embrace, he accepted his doom with a deep, pure, and utterly happy smile.

Finally, Washen asked, “What work are you doing?”

“Something small,” he said.

She waited.

“I made a list,” he reported. And of all things, he produced the huge wing of a copperfly—the first parchment used by the captains when they were marooned long ago on Marrow. “A little list.”

“Good,” she offered.

He unfolded the wing along its natural seams, bending it so that only his eyes could see words written by his own hand.

“What sort of list?” she inquired.

“Just some obvious questions,” he replied.

“Such as?”

“Obvious questions,” he repeated. He had his father’s energetic eyes, but his silences reminded Washen of her own mother. Every few years, Washen again realized that Locke and his grandmother were rather similar creatures. Except that the old woman had been swallowed up by the exacting, impatient business of engineering—a rigid realm of perfect knowledge drawn across a thoroughly defined existence.

“What is obvious?” she pressed.

He said, “I’m sure you’ve asked these questions yourself. Probably thousands of times, I would think.”

“Show me.”

He considered the request, but then the hands began to refold the tough ruddy wing. “Not now.”

“A glimpse, maybe?”

He shook his head, stowing the wing out of sight.

“Really,” she pressed, “I would love to see what you’ve asked.”

But her son was woven from sterner stuff. With a gentle shake of the head, he repeated, “You’ve asked these questions yourself. And if you haven’t … well, Mother, then seeing them now isn’t going to help much, is it … ?”