On the carpet they go. "How d'you triangulate like that from a scry?"

"Angle of shadows. - do you know anything about how the movements of the world and sun work, it occurs to me that drow don't really have any reason to -"

"I was in school for seventy years, we may have covered it, but that doesn't mean I recall."

"So the world orbits the sun. It's hard to get an intuition for it because it only works the way it does since they're both absurdly big and absurdly far away. The seasons are caused by the world being tilted with respect to the sun, which affects how the light hits it, and light hits different places on the surface of the earth at different times, so if it's noon in Sothis it's going to be noon in a bunch of other places -" he makes himself an illustrative illusion to help - "on a line, like this. And as it stops being noon, the shadows get longer. To figure out where someone is you need to be able to measure how long a shadow is in the scry, and it needs to be the shadow of something whose height you approximately know - like a person. Then you can calculate how far past noon it is, where they are, and then you can draw a line that shows all the places they could be."

"How do you mean the world is tilted? It's a sphere, it's the same all round."

"Relative to how it's spinning around the sun, I mean." He frowns at his illusion for quite a while until he can get it to show this.

"Oh, huh. ...leave that up for a bit so I can look it over?"

"For sure! I haven't explained it before, there's probably a cleaner way."

She studies the illusion and draws a simplified version in her notebook.

"It's not relevant to tracking the shadows but the force that makes the planets orbit the sun is the downforce. Like the way a marble will spin and spin and spin around a funnel, except that the marble's losing some energy to the funnel and the planets aren't losing any to anything since they're in space."

"You realize you sound like you're talking nonsense."

"Didn't you tell me once you never went to school?"

"Yeah. Do they cover this in school?"

"Well, no."

"Bits of it sound familiar to me from, most likely, school."

"Maybe they cover it in drow school since there's more time to fill. I went to a good school and it was almost entirely accounting and composition and theology. Occasionally a guest lecturer about magic or global affairs."

"Most people don't do seventy years of it but I doubled up on magic and took lots of electives and tutoring sessions and stuff, I was very bookish as a girl and my mother was by this point trying to avoid having husband amounts of money and would pay my way into any class I wanted."

"She didn't want to marry?"

"She missed my dad and didn't want a replacement."

Nod.

"I was pretty young when he died but I think he loved her too."

"Awwwww."

"I mean, naively you might think it never happens, right, given the givens, but it seems to. Unless they're all faking it to cope, which back when I was musing a lot about whether I could ever possibly get married was very concerning and now is mostly just sad."

"Well, I don't know about the thing the drow are doing. I don't think Osirian women are all faking."

"If drow men aren't then Osirian women definitely aren't."