I think this book is one of the very few.
Cage's extravagant and uniquely enjoyable and humourous character is flowing out of these pages!
This collection of writings and lectures by Cage seems to me one of the most engaging reads on, about, and from music. Cage writes some of these texts not unlike he writes his own music, and the whole book is like a big koan - at points making sense, and then suddenly it doesn't. It is neatly accompanied with random little interludes of Cage's memories, a different text in capitals in the middle of the page, or just lots and lots of space.
It's a book I will keep returning to, and it's a book you can just start reading at any point - you don't have to start from the beginning. In fact, it's quite nice to just open the book at a random page and start reading from there; very refreshing indeed :)
This and Morton Feldman's Give My Regards to Eighth Street: Collected Writings of Morton Feldman (Exact Change)
I consider two of my all-time favourite books on music.