On Improvisation, Another Interest

Years ago, when I first began attending the workshops given by the late Arnie Lawrence, I told him that my goal was to learn to improvise. At the time, I thought it was a kind of technique that you could learn, and, in a sense, it is, but not in the way I thought it was.
On the one hand, improvisation isn't all that mysterious or difficult. Every time you open your mouth and utter a sentence, you're essentially improvising. When you're learning to speak a foreign language, it often takes a long time before you can produce new grammatical sentences in that language -- improvise in it -- and improvisation in music is very similar in that respect. You have to learn the musical language that you're improvising in before you can do it.
My goal was to improvise in the language of jazz, and it has taken me ten years or more of steady work to reach the point where I am beginning to feel confident in my ability to do it.
Earlier in the process, when it came my turn to improvise, I often felt like someone who has dived into murky water with his eyes closed, hoping to come up in a certain place, but never sure whether he'd reached it or not until after his head broke the surface and he could look around again.
Or else I felt as if the music were zooming past me at such a pace that I could never catch it.
The next step was playing relatively mechanically, repeating similar patterns over and over again, because it was hard enough to say to myself, "This is an A Major Seventh chord, and I can play certain notes over it," so I couldn't be in much control over which notes I played or how I played them, as long as they weren't wildly inappropriate to an A Major Seventh chord (though, in fact, if you play it in the right spirit, you can play any note over any chord).
I'm still more or less at that stage, but I'm getting better at choosing the notes and avoiding repetitive patterns (at least I think I'm improving at that). Improvisation involves a paradoxical combination of control and freedom. The best times in playing a solo are when you suddenly find yourself playing something that surprises even you, when you suddenly think of playing some notes that you've never practiced and never thought of before.
It's very much like what can happen in writing: an unplanned thought occurs to you - and it's the most important thought of all.