I read A Ring of Endless Light at least a dozen times as a kid, and you can tell. The pages have turned brown and the corners are worn to a round edge. Corners are ripped off, and the crease on the front cover is so distinct I'm surprised that part of the book is still intact. The spine is cracked clean, and the only thing keeping this paperback together is a good amount of yellowing Scotch tape.
I'm sure I know why I bought this book as a kid - there's a dolphin on the cover, and if you'd asked my Elementary self what the coolest creature was, "dolphin" would have been my answer. But why did I read it again? And again and again and again, until we have this almost broken book that most people would see as trash?