Maud came home from Genoa in the late summer, two years older and considerably less patient, carrying four bound notebooks and an opinion about nearly everything.
She had gone south at Corradino's invitation, with Cecily's blessing and Thomas's quiet encouragement, to spend a season in the house's workshops seeing what the Genoese did with water. The season had become two years. Her letters in that time had been short, infrequent, and composed almost entirely of diagrams, with the occasional line of prose appended at the bottom as though under duress.
The pumps here are better than ours. The mathematics is worse. Nobody writes anything down. I am writing everything down. Tell Wat — this in the first year, before the news had reached her — that their joinery is disgraceful.
She walked into the schoolhouse on the second morning after her return, sat at the back of Osbern's lesson on levers without asking permission, and at the end of it raised her hand.
"Master Osbern. That was wrong."
Osbern, who had been teaching for most of fifteen years, went a colour Thomas had not previously seen on him.
"I beg your pardon?"
"Not badly wrong. The principle's right. The example's wrong. You said the effort halves when you double the arm, which is true, and then you drew the fulcrum in the wrong place, and three of them copied it down." Maud pointed at the slate. "They'll get it wrong on Cecily's assessment and they won't know why."
There was a silence in the schoolhouse of the kind usually reserved for fights.
Osbern looked at the slate for some time. Then, to his very great credit — and Thomas never afterward said a word against the man — he said, "Yes. So I did," and rubbed it out and drew it again.
"You've made an enemy," Cecily told her afterward.
"I've corrected a slate."
"You've corrected a master in front of his pupils, on your second day back, without being asked." Cecily's tone was not reproachful, exactly. It was the tone of a woman who had been expecting this for two years. "I'm making you a visiting master. Two days a week. Mathematics and mechanics only. And you'll correct Osbern's slates in private or I'll send you back to Genoa myself."
"That's fair," Maud said, after thinking about it. "I don't like him, though."
"Nobody likes him. He's still a good teacher. Those two things are allowed to be true."
It was Thomas she came to find that evening, with the notebooks, and it was not about levers.
"I want to show you something that worried me," she said, and opened the third book at a page marked with a scrap of thread.
It was a drawing of a fever house. It was not Argenton's fever house, but it was very clearly descended from it — the separation, the ventilation, the water arrangement. And it was wrong in four places, each of which Maud had circled.
"This is in Pisa," she said. "A physician built it from a description. Not from the Codex — from somebody who'd heard about Aldith's methods from a merchant who'd heard about them from Corradino's factor. By the time it got there it was a story about a story." She tapped the circled parts. "The water comes in downhill of the sick room. They've put the linen store next to it. They lost more people in the first season with it than they did without."
Thomas looked at the drawing for a long time.
"There's more," Maud said. "Half a dozen things like it. Our scrip mechanism, garbled, in a Lucca bank's books. A wire run someone tried in Genoa because they'd heard we had one, with no idea what it was for. They thought it was a kind of bell rope." She closed the book. "We tell everyone the knowledge is free. It's free the way seed is free. You scatter it and it grows wherever it lands, and some of what grows is poison."
"What are you suggesting?"
"I don't know yet. I'm not suggesting anything. I'm telling you what I saw." Maud's voice was flat, the way it got when she was more upset than she wanted to admit. "Two years I watched people build things from our ideas without the parts that make them work. I used to think the danger was people stealing the Codex. I think now the danger is people half-stealing it."
She met Margery the next day, at Victoria's insistence.
Maud had, as far as anyone could determine, never held an infant in her life, and she held this one the way she might have held an unfamiliar instrument — carefully, at a slight distance, examining the mechanism. Margery, four months old, stared back at her with the unblinking, self-contained attention that had already become her defining quality.
"She's watching me," Maud said.
"She watches everyone."
"No, she's watching me. Not looking. There's a difference." Maud studied the baby with frank professional interest. "Send her to me when she can count."
"She's four months old," Thomas said.
"Then I'll wait." Maud handed the baby back, quite gently, and turned to go, and then turned back. "I mean it, though. I've met a great many children in the schoolhouse. Most of them look at things. Very few of them watch."
Victoria, holding her daughter, said nothing until Maud was gone.
"That," she said, "is going to be a problem in about twelve years."
"Which part?"
"Both of them," said Victoria.