The Mastery of Music: Ten Pathways to True Artistry by Barry Green, Broadway, 2005.
Well, I liked it.
It helped me realize a few things about my playing: why I prefer improvisation to learning "real" songs, why people usually respond better when I do that. Because my technique is crap, I can't let go and perform artistically if I'm trying to reproduce someone else's tune. In improv, there is no right or wrong, so no anxiety, so I can move with the music.
The book is more aimed at someone with a traditional music education, for whom technique is all-important. It tries to get past technique, to see what other qualities are needed to really soar as a musician - although it acknowledges, repeatedly, that you have to have technique. Joshua Bell doesn't just have soul, he also plays all the notes right.
So I took home sort of the inverse lesson. I don't claim to be able to "play in the Zone" at the drop of a hat, but when I improvise, I do play with more joy, more feeling, and I connect better with the audience. That part, I can do already. What I'm lacking is the solid technique and skill that comes from regular attentive practice.
(I played at church recently and two people asked how I got that neat note-bending effect. Um... I accidentally hit the string with my nail? I hadn't been trying to bend any notes, you see. This sort of thing should be cleaned up.)