Schoenberg called him a genius. Others called him wacky. So how does John Cage go down at the Barbican? Michael Dervan reports

Few well-known figures in 20th- century music have retained the capacity to divide opinion as surely as John Cage, who died in August 1992, just before his 80th birthday. His early percussion music, which used everyday objects along with percussion instruments familiar and exotic, won him a spread in Life magazine in 1943. His international notoriety was assured when, in 1952, he offered the world his "silent" work, 4'33", the title indicating merely the duration of the piece.

4'33" is not actually silent at all. By having the performer remain silent - in the original version, a pianist sits at a closed piano - it focuses listeners' attention on the incidental, ambient sounds that people usually try to exclude from their attention in the concert hall. "What I have wanted to do," said Cage, "is let the sounds be themselves and to let the listener do more and more - as Marcel Duchamp said, complete the work himself. So the important thing finally, I think you must agree, is the listening."

His abnegation of personal taste, by using the I Ching, the ancient Chinese Book Of Changes, to reach compositional decisions from the outcome of chance operations, cemented his reputation as one of the most original of musical thinkers - or, if you are unsympathetic, one of the wackiest avant-garde composers - of his or any time.

Arnold Schoenberg, inventor of the 12-tone technique, was one of Cage's teachers; he made the impoverished young man promise to devote his life to music for the privilege of getting inside the door as a pupil in the first place. Schoenberg famously commented that Cage was "not a composer but an inventor of genius" and warned of the consequences of Cage's limited sense of harmony.

The rhythmic world of percussion provided an obvious and immediate solution, and Cage's invention of the prepared piano - a piano with foreign objects inserted between the strings - gave the world a strangely haunting, one-man percussion orchestra that, alone, would probably have guaranteed him a place in the history books.

In the 1950s his exploitation of chance techniques and his interest in writing music that was indeterminate with respect to its performance influenced major figures of the European avant-garde, Boulez, Stockhausen and, later, Lutoslawski among them. Never had a US-born composer exerted such a strong influence on compositional trends in Europe.

Last weekend the BBC Symphony Orchestra's annual January composer focus offered a three-day programme titled John Cage Uncaged at the Barbican, in London. In one sense it was the most unlikely of orchestral undertakings.

Neither the orchestra as such, with its all-controlling conductor, nor orchestral musicians, often among the greatest sceptics when it comes to new music, seem to have agreed with Cage's temperament. He reduced the conductor in performance to a rule-bound semaphoring presence, mimicking the movements of the hands of a clock. And at the Barbican the dreaded spectacle of players giggling in the middle of a performance was not avoided, reminding one of Cage's comment that "this lack of devotion is not to be blamed on particular individuals . . . . It is to be blamed on the present organisation of society; it is the raison d'être for revolution."

The artistic planning of the weekend, it has to be said, showed a certain failure of nerve. The orchestral programmes were very light on music by Cage, offering instead a range of US contextualisations, the only European presence being Satie, through the ballet music Parade.

The weekend's most memorable orchestral performances were actually not of Cage at all but of Morton Feldman (Cello And Orchestra, with Paul Watkins and the BBC Symphony Orchestra under Pierre-André Valade), Ives (Central Park In The Dark under Lawrence Foster) and Varèse (Amériques under David Porcelijn). However, placing Aaron Copland's El Salón México in a programme with Cage's The Seasons and 4'33" seems to have caused perplexity all round.

It's often been said that Cage was less important as a composer than as a musical philosopher, an impression that the orchestral concerts might have reinforced. But the weekend also included a selection of early percussion pieces, given enthusiastic if sometimes rough and ready performances by the students of Guildhall School of Music & Drama Percussion Ensemble under Richard Benjafield, a selection from the iridescent and always surprising Sonatas And Interludes (1946-48), the major work for prepared piano, played by Rolf Hind, and the String Quartet In Four Parts of 1950, done with chaste sensitivity by the Duke Quartet. The immediate listener appeal of Cage's best work from the 1930s and 1940s is still one of 20th-century music's best-kept secrets.

The most illuminating events were to be found outside the concert hall. Films by Peter Greenaway, Elliot Caplan, Frank Scheffer and Alan Miller brought documentary footage of the man himself to the celebration at the Barbican. Cage blended sincerity, rigour and charm in a most unusual way. He was both seriously playful and playfully serious, and he seemed to shirk no implication, however strange, in the ideas he propounded. His purity of intent was as inescapable as his sometimes irrepressible sense of humour.

But it wasn't just the films that brought the spirit of the composer to the weekend. His fellow US composer Stephen Montague organised Musicircus, a musical "happening" - a Cage invention of the early 1950s, although the word was coined at the end of the decade by Allan Kaprow - that involved more than 340 performers.

These ranged from Gavin Bryars, John Paul Jones of Led Zeppelin, traditional Irish musicians and the gardening expert Stefan Buczacki to students and amateurs, who collectively turned the Barbican's disorienting foyers into a Cagean, chance-determined phantasmagoria through which listeners young and old, individuals and families, wandered with evident wonderment.

Cage, declared in the weekend's opening talk by Bryars to be the most important musical figure of the 20th century, would surely have approved.