Time keeps on slipping

The music is slow and quiet. Very, very, very quiet. And, it's very, very long. Three performers coax the sounds from their instruments. Wooden beaters barely touch the cold, steely surface of a vibraphone. Piano keys are depressed so softly that the player can almost feel the hammer move under his fingers. A bass flute whispers darkly - warm breath only just turns into notes. These sounds appear to be sourceless... and the piece is four hours long.

Soft, gentle chords for four hours. Piano and celeste, flutes and tuned percussion. No sweeping melody, no catchy rhythm, no arresting drama, no gushing emotion. Just soft, gentle chords - floating, colliding, disappearing. Notes at the threshold of hearing. For four hours.

This is For Philip Guston, composed in 1984 by Morton Feldman, and it is receiving its British premiere as part of the Planet Tree Music Festival tomorrow evening at The Conway Hall in London.

Feldman was a large-scale American with lank, oily hair and myopic eyes that squinted through black-framed pebble glasses. He could easily have been mistaken for a lorry driver or a motor mechanic. But he was a composer, and he produced some of the most profound music of the 20th century - almost all of it slow and quiet.

Not for him the carefully crafted scramble of the European serialists with their intellectual point-scoring and crash-bang-wallop sound world. While they composed the equivalent of Picasso's Cubism, Feldman created the kind of soft, dark resonance that comes off the surface of a painting by Mark Rothko. A great, misty stillness that induces quiet, timeless contemplation.

Feldman knew Rothko. In fact he knew most of those New York painters from the Fifties; so much so he once said: "If you don't have a friend who's a painter, you're in trouble." Some of them are mentioned in the titles of his pieces: Rothko Chapel, For Frank O'Hara, For Franz Cline, For Philip Guston. He also knew the composers Christian Wolff, Earle Brown and John Cage. Together with Feldman they became the bad boys of contemporary music, setting the tone of a generation in the glamorous heyday of Fifties New York.

These were the wild, post-war times that produced the Beat Generation, abstract Expressionist painting, rock'n'roll and the modern world. In the midst of this maelstrom Feldman worked with the idea of the individual sound. The sound that seems to come from nowhere, the sound that hovers and then slowly fades.

It was John Cage's work that gave him permission to do this; Feldman preferred the idea of "permission" rather than influence. The work of these New York painters and composers illuminated a "terrific green light. Up until then, everything was red light." Suddenly, everything was go.

Over in Europe, Stockhausen, Boulez and their crowd were rewriting the rules of harmony, melody and compositional structure and Feldman's idea that "the sound is the experience" was probably quite threatening. They were interested only in how the music was composed, as they rehashed the grammar, the syntax and the punctuation. The avant garde were trying to turn sound into a thing rather than a process.

In New York, the bad-boy outsiders were listening, really listening, to individual sounds and the way that sounds naturally combine and collide without any interference from composers. The Americans were not concerned with being avant-garde - moving on, out of history, into the next stage - simply because they did not have that much history to move out of. There was not the baggage of the post-Renaissance tradition that dogged Europe and generated its cultural superiority complex. The writers, the painters and the composers in New York just got on with it, and what they made had little to do with what had gone before.

The idea of the single sound has echoed down the decades from the Fifties. It is there in the work of other American mavericks who, over the years, have gradually become acceptable, even popular. La Monte Young, for example, the acknowledged "godfather of Minimalism" whose sumptuous drones can sometimes last for weeks.

Steve Reich, Philip Glass and Terry Riley all took the "single sound" idea and turned it into minimalism. Riley's early piece In C was recently performed by an ensemble that included members of Pulp and more of his early works also appear in this festival.

Eventually the "single sound" infected the likes of Brian Eno, whose idea of "ambient" music is concerned with "hearing music as part of the environment... at comparatively low levels, even to the extent that it frequently falls below the threshold of hearing".

Music that begins nowhere and, as Cornelius Cardew said of Feldman, "recedes from our ears". Cardew was a radical English experimental composer who was killed in a hit-and-run incident in the late Seventies. He was a major figure who championed Feldman's work in this country.

He also founded The Scratch Orchestra, a collection of composers and performers which created a great legacy that is still discernible today. Gavin Bryars, Michael Nyman, Howard Skempton and John Tilbury, the pianist on Friday night, all had connections with the Scratch Orchestra. Even Paul McCartney claims to have played with them once. This "orchestra" gave permission to the English Experimentalists of the Sixties and Seventies to inhabit the maverick world created by the Americans. Skempton is a great advocate of Feldman - "Feldman, for me, was the model" - and talks eloquently of the clarity, practicality and lack of rhetoric that produced an immediate intimacy. "Why did he have such success with girls? This great brute of a man? I mean he wasn't God's gift. I'm sure it was the possibility of intimacy that he presented."

But for many people this soft, quiet intimacy, continuing for four hours, may seem intimidating or simply boring. Four hours can be a very long time. And how do the performers cope? They cannot have a drink or a stretch or go to the lavatory. They are playing continuously, with incredible concentration, maintaining a steady tempo and a very soft, even dynamic.

John Tilbury is approaching his task with some trepidation: "It is quite daunting but I'm confident I can do it. It's not the four hours, it's the level of concentration. I'm playing two instruments, piano and celeste, and we're reading from the score, not from parts, which is in Feldman's handwriting - but I'm used to that. You can't really relax, but you have to relax to play it."

He also describes the difference between clock time and our real experience of time. Society cuts time into vicious chunks, then makes us fit into them; but sometimes five minutes can seem like for ever, whereas a whole day can slip by in the twinkling of an eye.

Skempton describes the piece as "companionable... like sitting on a beach with the sound of the waves. Easily done." Maybe it is like being in a bar all evening, watching the world go by or just mooching around on a Sunday afternoon: suddenly, four hours has gone and you have had a great time.

The Planet Tree Music Festival continues until 20 November (information: 0171-420 1000)