"Maybe you could halve it, and then halve it the other way, and then halve the quarters, and so on..."

"But if I halved it all the time how would I keep the parts always connected to me to keep affecting them?"

"Here, do the disk on your palm again."

She does.

Addy takes her hand and traces a cross across it, then an offset cross, like a sliced pie. "Like that, and then -" She draws a grid over the cross. "Like that, and so on, but it's always attached to your hand, just not to itself. Until you're holding a palmful of attached powder and can detach it all at once. Sound doable?"

"Yeah, I'll try that. And your hand's really cold, are you okay?" It's also kinda hard to the touch, but Sadde doesn't feel like that's a polite thing to say. She's not always tactful but by now she's grown pretty fond of Addy.

"I'm fine. Circulation thing." Addy lets go of her hand.

"What's tripping you up?"

"Creating new slices that are far enough from all others that they're not just widenings of another slice."

"Oh, that sounds like a good idea." Pause. "Couldn't I just use the sandpaper itself as I grow more bone to keep grinding it?"

"If you sand your bone to powder that's a way to get bone powder, sure, but it's not going to do a thing for your magic."

"I guess," she sighs. "I don't think we have any, though."

"I'll bring some tomorrow."

She grins. "Best teacher!"

"I try!"

"Alright, what next?"

"Non-blood fluids?" suggests Addy. "Without such a convenient mechanism as capillaries hiding the action from you."

"Producing or absorbing?"

"Both, of course, you don't want the wrong amount of lymph."

She giggles. "I'm not sure I want to start out with that. Saliva is probably still the safest one to try."

"Sure. No shortage of options. Leave spinal fluid for last."

And so it goes. It turns out that Sadde cannot convince her power to treat free fluid as if it were a part of her and shift it, but she can produce and reabsorb arbitrary fluids, which is almost as good. Her hunch about powder turns out to be correct as well, and it doesn't matter whence comes the matter. She can produce pretty arbitrary biological things, and stretch "biological" pretty far (producing, say, iron), but not too far (no gold). Eventually, the main limitation is practice time, human precision and human memory. Addy bids goodbye. Years pass.

Sadde is:

twenty-three.