It's outright my favourite manga, it manages to avoid most of the issues fantasy manga tend to fall into nowadays and it's remarkably mature and well-thought out in how it approaches a lot of its subject matter. It's also just a delight of a work when you analyse it.

Since you're quite early I'll go over one of the simpler things I had fun considering: the magic system! Without going too in depth, it functions as an allegory for several things at once, most notably art. Obviously the magic is drawn, but it goes further as the way that the witches relate to their magic is the same way artists relate to their art; they develop styles and preferences, they have to work around their lack of skill in certain areas to produce their art, the way people talk about it, etc...

But it also doubles as an allegory for scientific progress, one of the forbidden magics is medical, after all. And there's this lovely tension between the two. I'd go further but to really explain my thoughts requires a lot of later context.

It's a lovely series, and I adore it.