"Have you come to any conclusions about magical fertility?"

"I haven't actually looked into it other than figuring out that, yes, lots of hybrids."

"I wonder if that's where some of the human-like species came from originally."

"Yeah, I thought about that."

"It's probably not polite to ask but maybe there are books with the answer."

"Ooh, good idea, we should look."

"To the library?"

"To the library!"

Sarah leads the way to the library.

"So where would one look for this," she muses aloud.

There was a dragon section, is there a more general magical creatures section?

There is!

"It probably makes sense to start in the magical creatures section." She leads the way to that.

Magical creatures section!

"So where do we even start looking," she wonders.

"I haven't really learned enough to know." She glances at the titles nearby, are any of them introductory or historical?

There are lots of introductory ones, and some about sociology and the history of magical creatures' society and institutions, and some about the history of the interaction between humans and various magical creatures, and how to care for a given magical creature...

"I guess just take books that look related and see if they have indexes?" Putting words to action she gets out one of the books on the history of centaur society.

It has five hundred years of history but seems to assume the existence of centaurs as a given.

Well that's a bust, she'll look at another book or two about centaurs if she can find them then switch to goblins.

The first is more specialised and the second more general and dates back farther, but both assume centaurs have always existed, too.

There are a lot of things about goblins, and in particular about wars and rebellions. And money.

"I'm not finding anything. Do you want to ask the librarian? Not about our theory specifically, but the origins of magical creatures."

"Haven't found anything either so sure."

She walks over to the librarian's desk. "Hi, Ms Pince. Do you have a minute?"

"Hmm? Yes, dear, what is it?"

"We were wondering if there are any books on where magical creatures come from. Like did they just appear someday or did someone make them?"