"I might've had more trouble if I'd never heard of birds before. But I've heard them described, I just pictured them more like... bats. Bats... with... feathers? And hard pointy noses? Your swan sculpture makes a lot more sense than what I was thinking before."

"Their wings are structured differently. Bats have the equivalent of fingers spread out all through the wing and birds have the equivalent of an elbow here," she points at the main bend in the swan wing, "and a wrist equivalent here-ish, no fingers or anything in where the feathers are spread out. Plus their legs bend completely differently."

"Yeah!" says Dagna. "Actually, the way the swan stands kind of reminds me of a lizard? You know deep stalkers, how they hold their feet?"

"I didn't get a good, um, look, at any deep stalkers, but if they're lizards that makes sense, birds evolved from reptiles."

"Really? What do you mean?"

"Oh, um, I guess evolution might not have been figured out here yet - does anyone breed, say, nugs, on purpose, to be tastier or more docile or whatever?"

"Yeah. And dogs, on the surface, and horses. Humans are always talking about their dogs and horses," says Dagna.

"Okay, so that's a small-scale version of evolution, except that people aren't usually the ones doing it. Animals die a lot in the wild, and the ones that don't are the ones that get to have the next generation, so animals are changing really slowly all the time to be better at resisting diseases and the local weather and predators, and at finding food and water and shelter and mates. They're trying to do all these things at once and there's a lot of luck involved, so it happens really slowly; people breeding things can get specific traits faster because they can concentrate on just that, make sure nothing else kills the animals they're looking after, and micromanage which animals breed with which other animals."

"That makes sense," says Dagna. "So, wait - the same thing to start with turned into lizards and birds because different things were happening to them? How does that even happen? How do dragons fit into this? Some lizards tried flying one way and got birds and some tried flying a different way and got dragons? But I guess I don't even know if dragons are properly lizards, if birds are then dragons could be secretly bats or something, how do you check? Are bats birds? I mean lizards?"

"I actually don't have a clue how dragons happened, because gaining limbs is pretty unusual and mostly only happens if something is evolving to stop being a swimming thing and start being a land thing. Losing limbs or changing them into a different kind of limb is much more common - that's how lizards turn into snakes or some kind of mammal turns into bats. Things might work differently or have exceptions here compared to my world, although if horses and dogs exist and are bred that implies the basic idea's still working. Dragons might not be lizards at all, they might just be something else with scales and stuff. Or maybe somebody made them without all the steps in between somehow. Anyway, bats aren't birds or lizards, bats are mammals, like we are, or nugs. I'm pretty sure mammals have been a different thing from reptiles or birds for a really really long time. Bats and birds had to do flying separately - so did bugs. But it happens a lot because it's really useful to fly, and it's still useful if you can only kind of fly, it lets you fall out of trees safely if you can just sort of glide and that means you can get away with moving around up there more recklessly and leaping away from anything that wants to eat you. And then - this takes millions and millions of years - eventually if enough of the glidey animals don't get eaten and gliding keeps being useful you get flying!"

"Wow," marvels Dagna. "That's amazing! I never knew animals were so amazing!"

"Mm-hm. And plants do this too... and diseases do it, which is less good... Oh, and there's also an actual reason why stuff has similar traits to their parents, living things are made of teeny tiny cells and each one has really tiny instructions written in a weird chemical code in there and those get replicated every time somebody grows a new layer of skin and needs more cells, or if they have a kid - most species it's half instructions from each parent."

"...I'm not sure I understood that," says Dagna. "Could you explain it again?"

"Um, I can try. I'm not really a biologist. So - if you look at a living thing or for that matter a recently dead thing under the microscope, it's divided up into little bags of mostly water. Trillions of them. And some things like bones and hair that are other stuff, but like, the meat parts are little bags, called cells. And those have littler things in them that act like tiny organs for the cell. And one of them is almost like the cell's brain, like, it's not smart, but it tells the cell how to do cell things and how to make cell stuff. And every cell in a specific living thing has the same memories written into every cell brain thing. And they are written very very small because you have to fit these inside tiny organelles inside tiny cells and you have trillions of them. The smallest things stuff can be made of are called atoms... well, the smallest things specific stuff can be made of is called atoms, like, the smallest amount of gold you can have is one atom of it but actually the atom has parts - anyway two or three or a bunch of atoms together are a molecule and that's how you get stuff more complicated than gold or whatever. And the instructions are a molecule. It's shaped like a twisty ladder, we just found that out pretty recently... And there are four different ways the molecule can be at each rung of the ladder and they spell out coded instructions for how to be a cell in a living thing and they're different for everyone except identical twins."

Dagna listens in delighted fascination to this whole explanation, and then she says, "...What's a microscope?"

"It's a tool for looking at really small things, it involves lenses. Sort of like a telescope? Only for things that are nearby and tiny instead of far away and regular sized. You can see cells that way but not atoms, they had to figure out atoms differently."

"How do you figure out atoms? I want to figure out atoms!"

"I don't know - I'm really sorry, I never focused very much on science in school, and I didn't have time to memorize any textbooks before the accident. Every day I'm taking some time to write outlines of things I know that might not be known here so I can eventually write books and share them around but they're all going to be layperson's knowledge based on pure unprepared memory."

"Well - that's okay, I guess," she says. "It can't be that hard to figure it out again from scratch... I'll think about it after I learn everything there is to know about magic."

"It might be pretty hard, because what they teach in school is almost all about results and not about how any of the things were learned. I think my world is hundreds, maybe even a thousand, years ahead of this one in technology, and that's at their pace; here you have Blights to deal with that my world doesn't. And, even if I remember things right, they might be mistakes; scientists sometimes make those when they're finding things out. But I still think it's better than not trying to share the knowledge. So I'll write a book on what I remember about biology and what I remember about physics and so on."

"Good luck with that!" says Dagna earnestly. "I look forward to reading it!"

"If you like you can read through it before I publish, and catch me accidentally not explaining microscopes and things."

"I'd be happy to!"

"Great. I'm not sure when I'll have it done. I'm trying to get enough that I don't forget things all down but organizing it into a book is harder."

Dagna nods sympathetically. "Maybe I should start keeping copies of a bunch of my notes on me in case I end up in another world somehow and need to write a book about everything I know..."