He looked at her gravely, and assessingly. "Perhaps Slytherin won’t be such a problem for you after all. And they’re not exactly forbidden. Well, maybe a few books are. Such studies are very frowned upon by most people in the Ministry. You won’t find any books about the Dark Arts themselves in this store, apart from joke jinxes and hexes. You could try Moribund’s, in Knockturn Alley – it has a selection of interesting books. I got one all about ghouls for Yule. It’s opposite Borgin and Burkes, next to the Spiny Serpent. But they’re not going to sell anything like that to a ten year old."