The piano player who sounds like an orchestra

"I accept this citizenship because it symbolises the everlasting bond between the Israeli and Palestinian people," said Barenboim at a press conference afterwards.

He received the official paperwork at the end of a piano recital in Ramallah in the West Bank at the weekend. He earned the honour for his work in promoting cultural exchange between young people in Israel and the Arab world, notably in the West-East Divan Orchestra he founded in 1998 with his Palestinian writer friend, the late Edward Said.

The fearless Barenboim, who has blithely scorned sanity and safety by conducting Germans playing Wagner in Israel, thrives on danger. With enough happening in his public and musical life to satisfy an entire army of king-sized egos, he is about to take on one of the greatest of all musical challenges. Starting at the end of this month, in eight solo recitals, he will play Beethoven's 32 piano sonatas at the Royal Festival Hall.

On the same day, he will be awarded the Royal Philharmonic Society's Gold Medal for outstanding musicianship, music's nearest equivalent to a Nobel Prize. Former recipients include Brahms, Rachmaninov and Stravinsky. Fittingly there's a Beethoven connection: the medal, introduced in 1870 to commemorate his centenary, bears his scowling effigy.

"Struggle, Beethoven is all about struggle," Barenboim says, spitting out the last word with a guttural force to match its meaning. "With this greatest of composers there's always resistance, battle with his own visionary torments." He slices the air with both hands, clenching right fist over left in imaginary combat to illustrate his point.

"There's never mere virtuosity for its own sake. Unlike Mozart or Chopin, Beethoven doesn't flow. You need to push him or pull him and sometimes he just stands still, stubbornly."

Barenboim first played the cycle as a formidably gifted teenager in Tel Aviv in the late 1950s. During his Swinging London years, 1966 to 1969, when he and his late wife, cellist Jacqueline du Pré, first made an impact as music's golden couple, he recorded all the sonatas for EMI.

Nearly two decades later (1981 to 1984), his interpretation by now more mature and poetic, he issued a second set, on the Deutsche Grammophon label, and has since played them again in concert. Half a century on, how does he keep them fresh?

"These sonatas are full of mystery and complexity. They're like a journal of the composer's life. People talk about Beethoven being heroic, a Titan. But what fascinates me is the other side, the gentler, more pastoral aspect of his wild, complicated character."

To listen to Barenboim is to be given, in each sentence, a gem-like encapsulation of musical history: "For Schubert, the same is true of his songs. For Mozart it's the Piano Concertos. But Beethoven's sonatas are on another level of revelation." What characterises one pianist over another, Barenboim over the handful - Mitsuko Uchida, Andras Schiff, Alfred Brendel - who play this repertoire with equal brilliance? Other pianists often observe that Barenboim, rare in sustaining a dual career as conductor and soloist, truly achieves an orchestral sound in his playing.

This is the goal of any pianist. Since Barenboim spent 15 years as Music Director of the Chicago Symphony Orchestra and is now Chief Conductor for Life of the Deutsche Staatsoper Berlin and Maestro of La Scala, Milan, he has an enviable advantage.

Compared with many musicians, his physical gestures are minimal, almost cool. This can make him appear detached. Yet as a pianist his clean, nimble fingerwork, often described as "crystalline", and his ability to let the music speak are precisely the qualities we value. Watching him on DVD or YouTube you can see, even in a simple gesture like the slow rolling over of a hand that Barenboim, ever the alpha male conductor, is in absolute control.

This is true away from the keyboard too. We meet in his conductor's room at La Scala - impersonal, formal, gilded. Barenboim, in contrast, is woolly haired, stylishly scruffy, owlish, unexpectedly mellow. He talks fast, says only what he wants to say, no more, no less, tacitly challenging you to keep up.

He says if he could put music into words he "wouldn't need to play the piano". Yet he is a skilled writer and speaker who gave, hair-raisingly for those involved, the BBC's Reith Lectures two years ago. An English edition of his new book of essays on music will soon be published by Orion.

Born in 1942 in Buenos Aires, Barenboim began piano lessons aged four, with his Russian-Jewish parents, both of whom were accomplished players. It was his father, Enrique, however, who really became his teacher.

In 1952 the family moved to Tel Aviv. Barenboim's extraordinary pianistic talent was quickly recognised by the great conductor Wilhelm Furtwangler. As a teenager, he began studies in conducting and, in Paris with the French guru Nadia Boulanger, composition.

One of his party pieces, which leaves even top musicians flabbergasted, is to be able to hear any piece of music through once then sit down at the piano and play it back by ear, virtually note perfect. This is the kind of rare, Mozartlike facility few have. Barenboim will play the Beethoven sonatas from memory. "And yes, I may make mistakes. It would be silly to say otherwise." Does his musicianship, in whatever form, still come easily?

"I try to be sensible, not to stay out too late or eat badly, but there's no particular regime. I work when I am free to do it. And when I'm playing the piano, I don't believe in rituals before concerts as some do." The great Shura Cherkassky, for instance, used to wash his hands obsessively, requiring a particular white towel on which to dry them.

Even the less neurotic usually follow some reassuring pattern of behaviour before a performance. Barenboim, famous among journalists for giving green-room interviews when the bell is already ringing to call him on stage, snarls at the very notion. "So if I say, before I play I must eat an orange, what happens when I am in a place without oranges? Do I go home? Do I say, I cannot possibly play because there are no oranges? No. I do what feels right at that moment. Basta!"

Alongside his Beethoven series, as if that wasn't enough to occupy his fertile mind, Barenboim is spearheading the first Artist as Leader forum at the Southbank, a series of debates on culture and society with Jon Snow and others. "Music," Barenboim argues, reiterating a familiar theme, "is not something detached from life, in an ivory tower, though some try to treat it that way. It's the greatest bridge between individuals, between societies that we have."

This humanitarian dream was the starting point for the West-East Divan, which will celebrate its 10th birthday at this year's Proms. "OK, sure, music invites you to forget the world. You come home from a stressful time at the office, put a CD on, put your feet up and wipe out the day. I understand that. But music also gives you an invitation to understand the world. It teaches us to listen to one another."

He means this not in a vague touchyfeely way, but with specific, technical application. "In music, one phrase answers another depending entirely on what has gone before. Think of a Bach Two Part Invention: one hand starts the theme, then the other replies."

For once his mercurial train of thought is easy to predict. "Imagine if politicians listened to each other and responded in such a thoughtful way!" He chortles at the idea. But as ever, Daniel Barenboim, citizen of the world, is being deadly serious. Make no mistake, he has put his life on the line for his beliefs. He dares us to sit up and listen.

Daniel Barenboim's performances of Beethoven's 32 piano sonatas, in eight solo recitals, are at the Royal Festival Hall from 28 January to 17 February (0871 663 2500, www.southbankcentre. co.uk). Six DVDs, Barenboim on Beethoven, are available on EMI.