"Oh. I sort of knew what a planet was."

"I wanted to try to avoid leaving inferential gaps."

"Yeah it was only sort of."

"Can you give me a demonstration of some of sorcery's capabilities?"

"I assume you don't want to be a sparrow."

"Not permanently."

"If you want to be one temporarily I can turn you back after."

"Better to establish whether I can do anything while a sparrow now than later."

"How long should I leave it?"

"Not longer than five minutes."

"Okay. We'll have to be in Fairyland, sorcery only works there."

Step. Sparrow.

Hop hop headtilt-

She can still feel the Force. Rituals are beyond her, no gestural capacity, but she can still be the fastest jumping sparrow Promise has ever seen- ah, flight instincts. Good. And lightning...? Zzzap. Good.

"...wow." Promise turns her back.

"Slightly inconvenient, but not altogether debilitating. Could another sorcerer undo it?"

"A really good one could, but it would take longer."

"Still to be avoided if possible, then."

Nod. "They'd need at least a good look at you. I need minutes, but I've had that, and now I can cast on you."

"The time required is a function of expertise?"

"The familiarity required, and the time required to establish that familiarity, is."

"What are the mechanics at work?"

"What do you mean?"

"You say familiarity, familiarity with what? Are you manipulating something about me or something else?"

"You and wherever you are; I could have done with less familiarity with you if we were somewhere I knew well."

"What is it about the area that matters?"

"Location and nature of matter, temperature, light passage, humidity, that sort of thing - and also harmonics, which are a purely magical property that has to be learned about by the use of sorcery in the first place. Good sorcerers can cast on observation alone, but knowing the harmonics is better."