Alvin turned slowly. "How do you know that?" said Alvin. "How do you know what it costs me to do that work?"

" 'Cause it's easy for you. You do it like breathing."

"And when you run up a hill, how easy is it to breathe?"

"Maybe I'd know what healing was like if you ever tried to teach me."

"You only just started hotting up metal."

"So I'm ready for the next step. You're working so hard on healing those children, I know you are. So tell me, show me what to do."

Alvin closed his eyes. "You don't think I wish you could?" he said. "But you can't help if you can't see what's going on inside their bodies. And Arthur Stuart, I tell you, you got to be able to see pretty small."

"How small?"

"Look at the thinnest, smallest hair on your arm," said Alvin.

Arthur Stuart looked.

"That hair is like a feather."

Arthur Stuart tried to get his rudimentary doodlebug inside that hair, to get the feel of it like he got the feel of iron. He could almost do it. He couldn't see the featherness of it, but he could sense that it wasn't smooth. That was something.

"And each strand of that feather is made of lots of tiny bits. Your whole body is made of tiny pieces, and each one of them is alive, and there's stuff going on inside those pieces. Stuff I don't understand yet. But I get a sense of how those pieces are supposed to work, and I kind of... you know..."

"I know," said Arthur Stuart. "You tell them how you want them to be."

"Or ... sort of show them."

"I can't see that small," said Arthur Stuart.

"Bones are easier," said Alvin. "Bones are more like metal. Or wood, anyway. Broken bones, I bet you could fix those."

Immediately Arthur Stuart thought of Papa Moose's foot. Was that a problem with bones? Was Alvin maybe hinting something to him?

"But the yellow fever," said Alvin. "I barely know what I'm doing with that, and I think it's out of your reach so far."