For two days during and after the ashfall everyone had stayed inside, doors closed and windows locked, until Dr. Dvali announced that the ash wasn't particularly harmful. Eventually Mrs. Rebka told Isaac he could go out at least as far as the courtyard gardens, as long as he wore a cloth mask. The courtyard had been cleaned but there might still be remnant dust in the air, and she didn't want him inhaling particulate matter. He must not put himself at risk, she said.

Isaac agreed to wear the mask even though it was sweatily warm across his mouth and nose. All that remained of the dust was a grainy residue silted against the brick walls and the rail fences made of never-green wood. Under a relentless afternoon sun, Isaac stooped over one of these small windrows and sifted the ash with his hand.

The ash, according to Dr. Dvali, contained tiny fragments of broken machines.

Not much remained of these machines, to Isaac's eyes, but he liked the grittiness of the ash and the way it pooled in his palm and slipped like talc between his fingers. He liked the way it compressed into a flaky lump when he squeezed it and dissolved into the air when he opened his fist.

The ash glittered. In fact it glowed. That wasn't exactly the right word, Isaac knew. It wasn't the sort of glow you could see with your eyes, and he understood that no one else in the compound could see it the way he did. It was a different kind of glow, differently perceived. He thought perhaps Sulean Moi would be able to explain, if he could find a way to pose the question.

Isaac had a lot of questions he wanted to ask Sulean. But she had been busy since the ashfall, often in conference with the adults, and he had to wait his turn.

* * * * *

At dinner Isaac noticed that when the adults discussed the ashfall or its origins they tended to direct their questions to Sulean Moi, which surprised him, because for years he had assumed the adults with whom he lived were more or less all-knowing.

Certainly they were wiser than average people. He could not say this by direct experience—Isaac had never met any average people—but he had seen them in videos and read about them in books. Average people seldom talked about anything interesting and often hurt each other savagely. Here in the compound, the talk was occasionally intense but the arguments never drew blood. Everyone was wise (or seemed to be), everyone was calm (or struggled to give that impression), and, except for Isaac, everyone was old.

Sulean Moi was apparently not an average person either. Somehow, she knew more than the other adults. She was smarter than the people to whom Isaac had always deferred, and—even more perplexing—she didn't seem to like them very much. But she tolerated their questions politely.