"Well, yes." She changes her mind, always curious about the workings of the Great Library and its sole librarian. "How do you find out when a book is missing?" "It is a matter of elimination," Inric says. "There are catalogues for the books in each room. If a book is missing, and Copper cannot locate it within the library, then it must have travelled." "And Copper can track it to a different world?" "Yes." "Can all the bookwyrms do that?" "Only with training." "So it isn't just about stopping them eating the books?" "That is the first concern," Inric says, straight-faced as always. "But no, it is not the only thing they need to learn."