The Vintage Guide to Classical Music by Jan Swafford

If you've ever wanted to dive deeper into classical music, this guide by Jan Swafford is a fantastic place to start. It covers a huge chronological history of music and includes essays on nearly a hundred different composers, looking at their lives and their most famous works. It's also got a really helpful glossary of musical terms and some great advice on how to build your own library piece by piece. It's a solid resource for anyone from a total beginner to a longtime listener. Used, but in good shape.