I don't keep a physical library of all the books I've read or listened to. I don't see the point in keeping a book unless you are going to be reading it again or in the case of art books, constantly referring back to it for inspiration and ideas. And since I travel a lot and move to a new city almost every year, keeping a library of books to show off to friends is not really a possibility. So I display the books I have read here in my Imaginary Library.