Sometimes a book title is a no-brainer. "Herzog." "Mating." "Cujo." But sometimes writers get directly inspired by other works, and that seed of a title worms its way in from a fleeting line the writer had once glanced on a page. Take, for example, John O’Hara becoming dead set on titling his masterwork "Appointment in Samarra" by that name because of an Arabian tale he read about in Sheepey by W. Somerset Maugham. Within that huge group of books whose titles reference other works, there are a number that borrow a line of poetry for their title. Here are some of our favorites.