Keith Jarrett, the award-winning jazz pianist who will make his classical concert debut at the Kennedy Center Concert Hall on Sunday, insists that ego has nothing to do with this very major career move.

"If it did, I'm sure the music wouldn't be any good and soon the people would stop coming," Jarrett says. "I don't find that ego and art can live inside each other too well."

Which may surprise some fans who perceived Jarrett as a brilliant but self-centered composer and improviser whose technical and imaginative skills were as astonishing as his behavior was patrician. He first made a name for himself in the late '60s with Charles Lloyd and in the early '70s with Miles Davis, and though he has led two highly acclaimed quartets -- one American, the other European -- he is perhaps best known as a solo artist.

"What I was doing over the last eight years was mostly solo-improvised piano concerts, but the meaning has temporarily been lost," he says. "For a while, the thing was very vital and there could be something established in the halls beyond clever little notes. The audience played a large role in that process, and as long as they were open to the process, I could have gone on with that forever because I was always starting from point zero.

"But after a certain amount of years and a certain amount of concerts, the audience started to become comfortable in this situation and started not to realize that the process was as primeval as it always had been. They weren't able to get down to that place where they could really observe what was going on, and since I needed them so much for input, since the notes were coming from nowhere, they were either going to be coming into an open room or a room full of expectations. And once they hit the expectations, the music started being not able to survive.

"People started to think they knew exactly what I did at these concerts, and I still didn't know what I did. I never really wanted to know. In order to preserve the process, well, it was a straight line from doing that to doing this."

Jarrett hopes to close the distance between the discipline of classical music and the imagination of improvisation. "Twenty years ago we didn't have a tradition for improvising, but we did for written music, for how to play all the pieces that were written a hundred years ago. There were enough scholars, and treatises written about the ornaments of the music in the days of C.P.E. Bach that you couldn't really get away with playing the music just having looked at the notes, because you'd have to know something about the era. I think you both lose and gain from all this.

"What we gained was information, but what we've begun to lose is the actual music. When C.P.E. sat down to play his own music he was not thinking about correct trills, because those trills were correct on the instrument he played and in the time he lived. Yet, because 'intelligent' people have, out of some sort of commitment to 'truth,' developed through all the little clues what is the 'correct' way to play this music, the music starts to be forgotten and just how to play it becomes important."

On the jazz side, Jarrett says, it's exactly the reverse. "It's not cool to be articulate about the music. You're just supposed to be playing it and doing it, and if you're not doing it, no matter what you say, it doesn't make any difference -- the music speaks for itself. So there are no scholarly possibilities there. But then the listeners don't understand how the music is played, they only know how to listen to what is played."

Jarrett occupies a middle ground. "The amazing truth is, it is more personal to play the music of other composers than to play my own improvised music, because I can actually relate to the music that I'm playing -- whereas when I'm improvising, there isn't any time or space to relate to it."

Although his move to classical recitals was hard and well-considered, Jarrett is no stranger to the discipline. He started on piano at age 3 and studied intensely for 12 years. His program Sunday will be heavy on Baroque: Bach (J.S. and C.P.E.) and Scarlatti, as well as Beethoven and Shostakovich. "Those composers are closer to what I feel I do than anybody else," he says, adding that most of them happened to be the major improvising keyboard artists of their day. "That comes second in my list of priorities, but it's funny that everyone turned out to be an improvisor of major stature."

There is also a spiritual subtext connecting Jarrett and those composers, a sharing of what he calls the "ecstatic state." "I consider Beethoven and Bach to have been ecstatics," Jarrett says. "Anyone who is a major improviser has to have some relationship to that, because improvising is all about transcending the subject matter, or transcending no subject matter, or creating subject matter, all of which are not possible in a normal state of mind. That's why I have a close relationship to the Baroque period, in that players were expected to be able to enter that state because they expected the music to allow them to mold it in a way that, from Romanticism on, we seem to have lost. I think there were no colored emotions in this music. It was a clear, transparent object that could be either made luminescent or allowed to be smudged up."

Except for one longstanding Japanese trio tour, Jarrett says, the classical commitment "is 100 percent what I'm doing." He had performed with a number of symphony orchestras over the past three years, doing Barto'k, Barber, Stravinsky and Mozart concerti, and "it led eventually to the question mark about recitals . . . When I finally realized that I was going to do it, everything else had to stop. I'm not going to play around with this."