"Hmmm," says Matilda, frowning. "But I don't think you're right about what's interesting. What if it takes a long time to explain because it uses a lot of concepts we've never seen before? I always think that kind of stuff is really interesting. And there's already more kinds of not-magic knowledge just in my world than most people would be able to learn in their entire lives even if they tried really hard, and before now there were a bunch of different kinds of knowledge that are actually wrong in my world but might not be in somebody else's. You could have kinds of magic that work by alchemy and kinds that work by quantum physics and kinds that work by geology, all different kinds of each one depending on how they work and what they do, and then you could have even more kinds than that because there's lots of worlds where the whole laws of physics work differently than they do in mine and there'll be sciences there I can't even think of. And I don't think that's boring, I think it's the opposite."