WAYNE SHORTER was rehearsing an updated version of ''Water Babies,'' one of his better-known works, for a concert here at the Spoleto Festival. His bandmates wanted to know how he planned to establish the tune's regular rhythm after a loose rubato intro. ''Let's not set it,'' he said. ''I'd always rather go for elusiveness than clarification.''
Oracular and penetrating, the statement was characteristic of this composer and saxophonist. At 68, Mr. Shorter is touring for the first time as the leader of an all-acoustic group. His quartet -- with the pianist Danilo Perez, the bassist John Patitucci and the drummer Brian Blade -- opened its tour, which will include American and European dates, at the Spoleto Festival on June 9. On Thursday it will make its New York debut when it performs at Avery Fisher Hall as part of the JVC Jazz Festival.
The critic Bob Blumenthal once called Mr. Shorter ''the jazz world's version of the Cheshire Cat.'' Mr. Shorter has said that he ''wants to create the sounds that people hear when they sleep,'' and he is renowned for his dreamy and vivid soprano playing and his seductively melodic compositions. But for all his accomplishments, Mr. Shorter is also well known for his inaccessibility; he is the kind of enigmatic figure fans love to marvel at and gossip about.
Throughout the 60's, he recorded all-acoustic sessions as a leader for Blue Note records and often toured as a sideman in the bands of Art Blakey and Miles Davis. Mr. Shorter was a founder, along with the keyboardist Joe Zawinul, of Weather Report, the group that popularized fusion in the 70's and 80's. In the last two decades, he has taken more time between recordings -- his 1996 ''High Life'' came after a seven-year hiatus from the studio. And like Sonny Rollins, Mr. Shorter has largely limited himself to special performances, like the 1996 appearance at Thailand's royal court by direct request of the king or his Lincoln Center showcase in 1998. At times, Mr. Shorter has been heard from so infrequently that he has seemed like a fugitive from his own career.
During a rehearsal break here, he talked about his new group, comparing it to the famous Miles Davis quintet he played in from 1964-70. ''With Miles we never thoroughly rehearsed anything, and no one judged one another,'' Mr. Shorter said. ''We were busy having a good time, and Miles wanted to have a group like that, where his responsibility was to create, and he didn't have to be a psychologist. Miles wanted to be entertained himself. He'd been playing longer than any of us, been on many stages. Everyone has to feel they're being entertained by each other. It was happiness at work onstage.''
Mr. Shorter's renewed sense of excitement was apparent to anyone watching him. In recent years, critics have sometimes questioned his engagement on the bandstand. Onstage at the Spoleto Festival, the quartet seemed upbeat and industrious. Each time Mr. Blade instigated a clever shift in rhythm, Mr. Shorter registered his surprise with a smile in the drummer's direction.
Since word began to circulate that Mr. Shorter was putting together a new group, fans have been curious about the music it would perform. Judging from the Spoleto concert, they will be pleased. So will his record company, Verve, which may release a live recording of the tour. The group's program was a retrospective of Mr. Shorter's work (though hardly a greatest hits revue), and there is a lot of ground to cover. He has produced one of jazz's great oeuvres, crowding out the likes of Ellington and Coltrane for space in the fake book, a collection of standards that is required study for most students.
Challenging the critical consensus that his structural and melodic innovations largely occured during his Blue Note years, Mr. Shorter eschewed some of his more familiar works like ''Footprints'' and ''Witch Hunt'' for later compositions like ''Atlantis'' and ''Aung San Suu Kyi.'' The arrangments were so radically different that the music reviewer for the local newspaper The Post and Courier found them melodically unrecognizable. Mr. Shorter had tampered with the sound of even his catchier melodies. ''Juju,''' for example, was played with jagged rhythms rather than its normal lilting time.
In his rehearsal of ''Juju,'' Mr. Shorter said: ''Let's do it multirhythmic all the way. The more contrapuntal stuff we use, the more it will sound like an octet.''
Mr. Patitucci, who's played on and off with Mr. Shorter for 13 years, explained the layering of rhythms this way: ''He always thinks compositionally. We play the tune in a straight rhythm that is African-oriented, sometimes in swinging time, and also very slowly, with almost a Brazilian feel. With all these options to choose from, Wayne keeps his rhythms swirling and pliable, and anything but predictable.''
However big or small the setting, Mr. Shorter thinks orchestrally and uses his horn to conjure swatches of sound with single notes. For years he has favored the soprano saxophone in concerts, but for stretches throughout the Spoleto performance he returned to the tenor, a move which will undoubtedly please fans who feared he had abandoned the latter instrument's deeper timbres. ''I don't think of myself as soloing on an instrument, per se,'' Mr. Shorter said. ''For me, the soprano's like a violin, and the tenor represents other strings like the cellos and violas.''
Mr. Shorter speaks as he plays: meditatively, with a fanciful arrangement of phrases; he answers questions obliquely, often with facetious digressions. When asked how he would decide which tunes to play on the tour, he replied, ''At this age it's really silly for me to talk about music definitively.'' Then adopting a playfully bombastic tone, he added: ''I can no longer say, 'I like this' or 'I want to do this.' ''
''Because music unto itself is neutral,'' he continued. ''Depending on the kind of life condition you're in, music can trigger a momentary response or it can be the vehicle for something that goes from heart to heart and someone who's going to commit suicide hears it and changes his mind. But I don't care if some of this is too deep anymore. As you get older, you start talking about exactly what's on your mind.''
HIS emphasis on the connectedness of life and music reflects his having practiced Nichiren Daishonin Buddhism for 28 years. He ended the interview to chant before the performance. The other members of the quartet ate sushi backstage and reflected on the experience of playing with Mr. Shorter.
''I feel like I'm in postgraduate school with Wayne,'' Mr. Perez said. Then he added: ''I hope the quartet can stay together. I'm ready to leave my band for this group.'' He may have been speaking with poetic license. The critical success of his group's latest album would in all likelihood discourage that move. But it was once customary for young jazz musicians to put their aspirations to become band leaders on hold while they served as sidemen to more established musicians, as Mr. Shorter did himself during his lengthy tenures with Art Blakey and Miles Davis. Today Mr. Shorter is one of the few living artists who could offer young musicians such an apprenticeship.
Mr. Perez, Mr. Patitucci and Mr. Blade had all played together in previous bands, and their rapport was apparent as they performed ''Aung San Suu Kyi,'' a piece dedicated to the pro-democracy leader who remains under house arrest in Myanmar (formerly Burma), which Mr. Shorter had recorded with the pianist Herbie Hancock on the 1997 album ''1 + 1.'' The ethereal ballad was energized in the hands of Mr. Shorter's new group, especially by Mr. Blade, whose whimsical yet controlled drumming is a perfect fit for Mr. Shorter's musical style.
As composers, Mr. Shorter's band members also contributed to the work's rearrangement. As the group rehearsed ''Aung San Suu Kyi,'' the band members discussed how to close out the tune. If they ended it on a tonic G chord, in the work's home key, the resolution would suggest peaceful accord. Mr. Shorter wanted a more anticlimactic ending, in keeping with the continuing political unrest in Myanmar.
Mr. Patitucci suggested an E-flat chord that would sound a more suspenseful conclusion. ''Yeah, that says we're still in Burma,'' Mr. Shorter said. ''We don't want to end on a tone of triumph. We can suggest triumph, but also connote caution and support.''