There are not many musicians who can conduct Mahler's Ninth at the Barbican one night and then return to the same hall a few weeks later to perform a piano recital of solo Bach. But in his various incarnations as pianist, conductor and cultural statesman, Daniel Barenboim has grown from child prodigy to an artist who takes a lead, and a stand, wherever he goes. "I think this is really one of the characteristics of our times," Barenboim remarks. "Postmodernism, if you want, means you can - and if you are a creative person you almost should - have multiple identities, based in other cultures. Paradoxically, only that way do you actually fortify each of these identities, because you are conscious of their differences."
Under the intent gaze of his hooded eyes, his trademark cigar wreathing his face in smoke, Barenboim is a powerful presence. The essence of dealing with the demands of such a life, Barenboim feels, is focus. "This is one of the reasons I felt forced to leave the Chicago Symphony Orchestra; so many things were taking so much time that did not have anything much to do with the music." He says his priority now is to tackle what he sees as the root cause of the ongoing threat to classical music. "I really want to explore ideas for what to do about music education. Because I think we are reaching a situation where the very future of classical music and its relation to society will be put into question."
The economic pressures facing musical organisations everywhere, from the Chicago SO to the three opera houses in Berlin, are, he says, "not the illness itself, but a symptom. The real illness is very simple: there is no musical education for young people. So why should they be interested in music? Why should music speak to a larger section of the population? You cannot become a successful lawyer or doctor and have a family and go to a concert for the first time in your late twenties or early thirties; if you have the bad luck to choose a night when I'm conducting the Schoenberg Variations, what can you get out of it? People keep talking about the crisis in the classical music world, concert life and the record industry. And of course it's too expensive for governments to support something that affects such a small part of the population. But why is that? Because there's no education! If music were taught in kindergartens, schools and high schools, then it would be of interest to a much larger percentage of the population and it would not be viewed as so expensive."
He has already begun to do something to bring about change. "I'm a firm believer in very early education. We've started a music kindergarten in Palestine as part of our music education programme there; it's very small, but the results are fascinating. I think we will open a music kindergarten in Berlin, too. And this is what the situation requires." The children, he explains, do some singing, begin to learn the piano and generally come into contact with, as he puts it, "the phenomenon of sound". "The most extraordinary thing about music," says Barenboim, "is that it expresses itself only through sound. I cannot explain to you the content of Bach's Well-Tempered Klavier or a Beethoven symphony. If I could do that, it would be unnecessary for me, or anybody, to play these pieces. But the fact that I cannot articulate them in words doesn't mean that there is no content. That content is the human condition: a human being's creation. That content, in the end, will also appeal to the children. They will find it important; and necessary; and fun."
His tenure as music director in Chicago has one more year to run. He doubts he will go back afterwards. As conductor in Chicago, at the Berlin Staatskapelle and elsewhere, he has tackled virtually every part of the orchestral and operatic repertoire. But it was as a pianist that Barenboim first conquered the world; and in this capacity he will be appearing at the Barbican on 1 May, performing the first book of the Well-Tempered Klavier. He will be performing the second book next January. The latter 24 preludes and fugues mirror the structure of the first book of 24, but find the older Bach exploring emotional territory that often delves even deeper into the potential of this intensely wrought genre.
Why Bach, and why now? "I grew up playing Bach," declares Barenboim, who was born in Buenos Aires in 1942. "I played Bach a lot as a child, from my first lessons onwards; my father, who was my teacher, believed strongly, and I think rightly, that Bach in general and the Well-Tempered Klavier in particular, was absolutely essential for learning to play the piano polyphonically, even symphonically. I stopped playing Bach for many years because I could not find the right approach; I had played it in a way that sounded very much like Brahms, at a time when the harpsichord was being regarded as the only suitable instrument for Bach's keyboard music. But I think that Bach's music requires the imagination to produce, on whatever instrument you play, the impression of all the different instruments that were available to him then - the oboe, the strings, the chorus, the organ and the harpsichord. This is why I think the piano is very appropriate for it. The art of piano playing is the art of creating the illusion of different sounds."
Barenboim has already recorded "Book One" of the preludes and fugues on Warner Classics; his recording of "Book Two" will be coming out this year. And it poses challenges of its own. "I find that many of the fugues in 'Book Two' are very choral in nature, less instrumental in many ways. And the weight and complexity of the preludes is much greater in this book." To perform each book complete is immensely demanding in terms of stamina and concentration. Nevertheless, Barenboim says, "I have played the complete 48 a few times over two successive evenings; it's a wonder- ful experience. For the audience, too, it's very special. You really do get a sense of finality when you reach the 'B Minor Fugue'; you feel you have reached the end of a journey." This concert is the latest stage in a larger, ongoing Bach journey for Barenboim himself: it will ultimately lead to his first performance of the St Matthew Passion in Berlin at Easter 2008.
Daniel Barenboim will play "Book One" of the Well-Tempered Klavier on 1 May at the Barbican, London EC2 (www.barbican.org.uk/020 7638 8891). He will play "Book Two" at the Barbican in January 2006
Jessica Duchen is a music journalist for the Independent and has written biographies of Korngold and Faure (Phaidon Press)