As conductor, pianist and latterly something of a statesman, Daniel Barenboim is one of the towering figures of our time. Not content with dominating the world's opera houses and recital platforms for half a century, he has recently begun to make a significant impact on the world stage.

With his East-West Divan Orchestra, in which young Palestinians share desks with young Israelis, he has arguably made more impact on the apparently intractable Arab-Israeli conflict than have most politicians.

His keenly awaited Beethoven cycle is the cornerstone of his incumbency as Artist as Leader at the Southbank, and last night's recital launched the series in characteristically intrepid style by including the formidable Hammerklavier Sonata.

Most pianists would prefer to work up to this Everest of the repertoire, pacing themselves on the lower slopes, acclimatising to the surroundings.

But this is a man who dares to conduct Wagner in Israel, a Jew who is not afraid to expose himself to his many enemies by playing in Ramallah in the West Bank. Barenboim is a man who likes to live dangerously and whose credo is articulated through his music-making.

He began his recital, however, with an early Beethoven sonata, indeed the first of the cycle of 32: the F minor, op2 no1. Both in this youthful piece and in the slightly later Sonata in E flat, op31 no3, he brought the most remarkable skills of communication to bear.

Other pianists such as Andras Schiff and Paul Lewis have impressed deeply over the past year or two with their own meticulously executed Beethoven cycles, but neither approached these works in the way Barenboim did, or approached his level of expressive mastery.

What Barenboim does so brilliantly is to recreate the character and mood of each movement - be it fiery, skittish, meditative or humorous - and to make us feel that he himself is discovering this music afresh.

But more than that, he unfolds each movement rather like an operatic scene with all its characters interacting: blustering, conspiring, chuckling. All life is there. Never before have I been so aware of the internal dialogues, the crosscutting, the sheer Mozartian vitality of this music.

If Barenboim's operatic experience is deployed to advantage here, in the Hammerklavier it's his Wagnerian staying power that sees him through.

The colossal grandeur of the opening movement, and the tireless energy of the Scherzo and fugal finale were already overwhelming, but what made the performance unforgettable was Barenboim's handling of the expansive Adagio sostenuto third movement, which traced the long lyrical arc of invention as though it were the most engrossing story ever told.

Musical communication of this order is rare indeed, yet is somehow intrinsic to Barenboim the man.

It was for that talent and for his outstanding, ongoing contributions to world harmony that he was presented after the recital with the prestigious Gold Medal of the Royal Philharmonic Society. By this time the packed audience was on its collective feet.

This cycle looks set to be one of the great experiences of the decade.

Daniel Barenboim's Beethoven cycle is at the Royal Festival Hall until 17 February, 0871 663 2500.