"Some magic systems come from within instead," Nina said, since she was a nerd about this sort of thing. "Like, if they want to light a candle, then they have to use their own energy to do it?????????? So, like, after that candle is lit, they might feel a smidge more tired than they were before????????????? Because the same sort of energy you physically use to light a candle was the energy that they used to light it with magic???????????????"

She reached over for another cookie.

"Then, like, there's systems of magic where it's based on drawing energy from the world around us?????????????? Like, every living thing has energy, right?????????? So some places learn how to make use of that energy to accomplish magical things??????????????"