Many musicians are fabulously skilled at playing the black dots on the printed page, but mystified by how the dots got there in the first place and apprehensive of playing without dots. Music theory does not help here; it teaches rules of the grammar, but not what to say. When people ask me how to improvise, only a little of what I can say is about music. The real story is about spontaneous expression, and it is therefore a spiritual and a psychological story rather than a story about the technique of one art form or another.
