"Oh. So I don't, but other people who like books might?"

"Yeah. Or even if you don't buy things, maybe you recommend the library to someone else who does."

"That makes sense. So the librarians also sell stuff?"

They take a breath as if to answer, and, looking rather overwhelmed, reconsider. "...It's more complicated than that and you can find a book about it."

"Okay, that's fair."