Wayne Shorter was 69 when he formed his own acoustic quartet, now hailed as the best band in jazz. He just hopes the music strikes a blow for original thought, he tells Stuart Nicholson

In 2002, composer and saxophonist Wayne Shorter unexpectedly returned to where many people thought he always should have been - the very pinnacle of jazz. The reason was the release that year of Footprints - Live! with a dynamic young quartet who seemed perfectly attuned to Shorter's demanding music.

The jazz world was united in its acclaim for the return to form of one of its most mysterious, yet significant jazz heroes. In 2003, The Academy of Arts in France named Footprints - Live! "Best Jazz Album", and it topped the polls in three Italian jazz magazines, the Downbeat Critics' Poll, the Downbeat Readers' Poll, the Jazz Times poll, and the New York Times Best of 2002 list.

Now the release of Beyond the Sound Barrier provides the latest update on Shorter's acclaimed quartet, as it delights audiences worldwide with its exciting, audacious yet intensely beautiful music. It is dubbed "the best band in jazz" by several US critics, and the album captures the excitement of live performances in Asia, Europe, and North America between November 2002 and April 2004.

"When we first came together we only had one rehearsal - one rehearsal!" enthuses Shorter at his Florida home. "And from that moment on we have never had any rehearsals. So when we go on stage and we're asked what we're going to play, we just say, 'Hold on to your hat!' "

The notion of not rehearsing - even new material - is usually a tricky concept to contemplate if you want to create meaningful music unless (a) you happen to be the world's greatest living jazz musician, and (b) you happen to have a band comprising the leading young musicians of their generation.

So as you might guess, there's a lot going on in Wayne's world that may not be immediately obvious.

To understand where he's coming from, it's necessary to rewind to the 1960s and the six years he played with trumpeter Miles Davis. As Shorter would later say, "with Miles I enjoyed the joy of not rehearsing".

The result was not - as you might suppose - a surfeit of leisure time off the bandstand and chaos on it, but a series of albums such as ESP, Miles Smiles, Sorcerer, Nefertiti, Miles in the Sky and Filles de Kilimanjaro that are artistically, aesthetically and conceptually among the finest achievements not only of jazz, but of 20th-century music.

So when Shorter came to form his own acoustic band in 2002 at the age of 69, he wasn't about to make life easy for himself. Ever the quiet revolutionary, he chose to adopt the same approach to bandleading he had learnt under Miles Davis.

The result has been Shorter's metamorphosis from a jazz hero, best remembered for his work between 1959 and 1985 with Art Blakey, Miles Davis and Weather Report, into his current high profile role at the forefront of American jazz.

This extraordinary change of fortune owes much to a meeting he had with his old boss in 1991. When Shorter went backstage, Davis cleared his dressing room of well-wishers and put his hands on Shorter's shoulders.

"Miles Davis told me in the dressing room - the last time I heard him play at the Hollywood Bowl - he said, 'Wayne, you need to be exposed!' "

In Davis-speak this meant he felt Shorter, who was then 58 years of age, was a bit of an underachiever. Four weeks later, Davis was dead. But Shorter, inspired by one of 20th-century music's most enduring and charismatic figures, decided to correct the ledger.

When he formed his quartet three years ago with Danilo Perez on piano, John Patitucci on bass and Brian Blade on drums, it was the first time he had toured as the leader of his own acoustic group.

The new band quickly sparked a creative renaissance for one of the most revered composers and improvisers in jazz, while in turn, under Shorter's guidance, his three young collaborators, each highly respected for their own work as leaders, attained new heights of creativity.

Today, Shorter is now receiving the kind of international acclaim for his audacious approach to music-making that would have made Miles smile.

With Beyond the Sound Barrier he has perfected a unique kind of chamber jazz that wouldn't sound out of place following the work of a mid-European classical composer like Lutoslawski, yet in the next moment might explode into jazz-rock rhythms.

Throughout the album, the music is a triumph of the unexpected, with Shorter's solos on soprano and tenor saxophones dramatic yet inscrutable as he plugs into the harmony of the spheres, his musical logic often suggesting a celestial third trumpet part.

Shorter passionately believes the dynamic, risk-taking elements of jazz improvisation are being lost after almost two decades of neo-conservative recapitulation of older jazz styles.

"My album Beyond the Sound Barrier . . . [ means] going beyond safe and sound, that's what all this music is about. 'Talking' about music - what makes someone do something musically - is not it . . . we know that when Miles Davis spoke to Wynton Marsalis, Miles Davis told him to shut up, and get his tone together," he laughs. "Because Wynton goes all over the world, speaking about, and trying to solidify what 'jazz' is supposed to be, what it is - what is pure jazz and what is not jazz - and he stops at somewhere after Louis Armstrong and runs flat into and embraces Duke Ellington!

"But this one mind knows nothing of the parameters of the vastness of human existence. Anyone who is going to fall for that kind of rhetoric gives me the reason why the bookstores in the United States are half empty. [ It is] not thinking for one's self and doing the hard leg work of reading Schopenhauer, Immanuel Kant, reading Victor Hugo, reading some great African writers, Asian writers, expanding oneself - it's not just N'Orleans!"

In the broader context of American politics, Shorter sees the pall of conservatism that has descended over America post-9/11 as antithetical to artistic creativity and something all creative artists must fight against, and he sees Beyond the Sound Barrier as a way of doing that.

"You know about the United States, with the 'Red States' and the 'Blue States'? The are so many 'Red States' that they're not taking any risks at all. That's what I am doing, musically, taking risks. Having the music reflect, for people to have the courage, to step out beyond these artificial barriers in life - their comfort zones, places of familiarity, hearing something familiar, only putting your money down on something that seems to have built-in guarantees and all that.

"That's why somebody has to strike a blow for original thought, and I am thinking maybe that the music we're doing will inspire people to be more individual in their decision-making, starting here in the United States, where it's needed badly."