The Joy of Music
A must-read for classical music listeners.
This is a book containing several essays, based on the famous concerts for young listeners.
This is a fine example of popularization of classical music.
As in many other fields of human endeavour, the more you know about it, the more you can fell in love with it.
You can like some classical music, but if you can appreciate it more thoroughly with some basic musical theory, you will like it even more.