I have never read this book and probably never will, but it's on my bookshelf. It doesn't even belong to me. It belongs to my best friend. At some point she lent it to me: "Yes, you can read it, but you don't have to. You can take it anyway." It is not the content of the book or the author that makes this book so special, but the fact that it is on long-term loan from my friend. I should really give it back to her at some point, really. About seven years ago, when I was graduating from high school, I lent this friend a book: Time Traveler's Wife by Audrey Niffenegger, a super cheesy love story about a time traveler. My friend has never read this book and probably never will. At some point she wanted to give the book back to me, and I told her: "The book is mine, but it's staying with you, so we have to stay friends forever!" Not giving these books back is a sign of the continuation of our friendship.
She keeps my book. I keep her book. And we remain friends.