Most readers have their own idiosyncratic systems for displaying the most valuable titles they own. For a lot of people, it makes the most sense to keep their favorite books on a particular shelf. At The Paris Review Daily, Sadie Stein writes about an odd phenomenon — “The Phantom Shelf,” which consists of books you love so much you had to lend them to friends. (Related: Kevin Hartnett on reading our parents’ bookshelves.)