East Neuk Festival is turning 10 this year, and to celebrate it is holding a pretty specialist kind of a party:

a Schubertiad. Basically this translates to an afternoon and evening of chamber music by the 19th-century Viennese composer Franz Schubert. There are trios, string quartets, songs and solo piano pieces, with various musicians - the Belcea Quartet, the Gould Piano Trio, soprano Malin Christensson, pianists Christian Zacharias and Llyr Williams - all mixing and matching to make up the various configurations. East Neuk's artistic director Svend Brown describes the event as a "quiet innovation" for the festival. "Sometimes it's good to just nail your colours to the mast," he says, meaning that for a festival whose reputation is built around the calibre of its chamber music, the intimacy of its venues and the loyalty of its musicians and audiences, there is no better celebration than a Schubertiad, epitome of all these qualities.

The origins of the Schubertiad go back to Schubert's own lifetime, when informal soirees provided a platform for the composer to perform his latest music. These events weren't strictly concerts - more unofficial, unadvertised gatherings of friends and neighbours numbering anywhere between a handful and a hundred. As well as serious music there was dancing and games of charades. Schubert and his friends drank good coffee and good wine and smoked long pipes of fresh tobacco. They read Schiller and Goethe and discussed philosophy late into the night. Think something along the lines of a traditional ceilidh, with impromptu turns of poetry and stories and songs cropping up between the dances.

Socially, the original Schubertiads were a mixed bunch. Young revolutionaries sat cheek-by-jowl with city merchants and princesses, all of them there for the love of Schubert's music. There was also a strong undercurrent of political unrest. The image of Austria in the early decades of the 19th century might look like a chocolate-box idyll, but it operated as a repressive near-police state in which artists - Schubert included - were subjected to regular censorship. As the nights at the Schubertiads drew on and the ladies retired to leave the men smoking and drinking, conversation would rally around political opposition, earning the gatherings a reputation for radicalism.

All the while, Schubert would perch at the piano, slightly removed from yet absolutely integral to proceedings. In his biography of the composer, the Viennese musicologist George R Marek describes something of the dynamic at these events: "every artist is a planet, minor or major, around which several moons circle. He, the artist, holds these moons in orbit by the force of his personality; his genius sheds a glow on those who would like to be artists but are not, or on those who are curious to explore the world of art - headier than their own world - or on those who merely derive vicarious excitement from knowing 'a celebrity'." Marek was writing decades ago but could easily be describing today's celebrity culture.

But the Schubertiads were more than hero-worship; Schubert needed them just as much as his friends did. Through the night he would play and play: new piano music and chamber music and songs, some of which he would sing himself. He would also accompany dancing and games; he was not above providing simple pleasures for the party. He died of syphilis at the age of 31 before achieving the large-scale success that would have surely come in later life. The Schubertiads were his testing ground, his stage.

Nowadays the political fervent and poetry has been lost, and what remains of the Schubertiad tradition is generally boiled down to a series of all-Schubert concerts with an intimate, informal atmosphere. Sometimes concert halls will ditch the usual rowed seating and arrange the audience around cabaret-style tables - fail-proof signifier of bohemianism. Often a Schubertiad is simply an excuse to indulge in several programmes' worth of some of the most tender and gratifying music ever written.

So why a Schubertiad at East Neuk? Partly it is simply that last point: Svend Brown has no qualms in claiming a director's prerogative to indulge his own tastes on the occasion of a big anniversary. "I love and am fascinated by Schubert probably more than any other composer," he says. "He is one of the few composers that I want to listen to at length." The fascination is "a little nerdy", he warns. "It's astonishing that at a time in Vienna when Beethoven and Rossini overshadowed all others, when so many composers either retreated from the field or slavishly emulated them, here was this very young man with very little public profile who revered and was influenced by Beethoven yet was utterly in possession of his own voice melodically, harmonically, structurally, poetically."

To understand what Brown means, just listen to the slow movement of Schubert's Death And The Maiden alongside the slow movement of Beethoven's Seventh Symphony: "Schubert's pervasive influence in the 19th century is astounding for someone who died so young, having published only a couple of hours' music." Poignantly, Brown describes Schubert's entire life as a kind of upbeat, without lasting long enough to enjoy its rightful resolution.

There's something else, too, that is fundamentally satisfying in Schubert's music. Brown calls it "a great urge to please the listener" - those extraordinary turns of harmony and melody that draw us in, let us engage and luxuriate. Perhaps the original Schubertiad set-up had something to do with this quality in the music; the fact Schubert knew his new works would be first heard by an audience that was up-close-and-personal - an audience that wanted to feel a part of the expression, whose reactions would be visible all around him.

Over the past decade, East Neuk has built up a loyal rostrum of visiting musicians, none more so than the German pianist Christian Zacharias. "I still can't really believe he accepted that invitation to the first East Neuk Festival," says Brown. "If you think of how we started: a small, wet-behind-the-ears festival in a part of Scotland that is obscure even to a surprising number of Scots, far less to international artists. By signing up for that very first festival and then returning every other year, Christian has put us on the map and contributed significantly to our identity."

Zacharias has played Schubert on almost all of those visits; the composer has long been the backbone of his career. "With Schubert," he says, "it's like sitting with a friend." But that friendship wasn't an immediate thing, Zacharias tells me. He hardly played a note of the composer's music until his mid-20s. "I had an old-school Russian teacher who had me learning Chopin and Liszt and Rachmaninov - 'real' piano repertoire. It was a generational thing; it took people like Schnabel and Brendel to wake us up."

Now in his early 60s, it was back around the age of 26 that Zacharias had his Schubert epiphany. At a concert in London he heard the great Romanian pianist Radu Lupu playing the Schubert's late G-major sonata, D 894, and the experience completely altered his approach to playing the piano. "Something clicked," he remembers. "The sound was so strong and unique and human - I wanted to be a part of it. It opened my ears. It was like hearing Monteverdi for the first time played by a dedicated early-music group."

For the Welsh pianist Llyr Williams, another East Neuk regular, it's the intimacy of East Neuk's concert settings - those small, beautifully simple churches in Fife's coastal villages - that makes this Schubertiad so appealing. "You lose something of Schubert's music if you put it in too big a space," he says. "Schubert's songs, for example, don't cope well with noise. They're so fragile and delicate, so private, so intimate. They are best heard at home, with friends and family sitting around feeling relaxed. East Neuk comes pretty close to that."

And how's this for familial atmosphere: Zacharias was the first concert pianist whom Williams ever met as a boy. At around the age of 10, at a concert in St Asaph on the North Wales coast, young Williams held out a book of Mozart sonatas for the esteemed German pianist to sign at the end of a recital. Despite sharing the bill of many an East Neuk Festival, the two pianists haven't met in the intervening 25 years. "Perhaps," Williams muses, "I might bring that book of sonatas to Fife this year, to show Christian. After all, we'll be sharing a whole day together."

East Neuk Festival's 10th edition runs June 27-July 6; the Schubertiad is at Crail Church on July 5. For the full programme, go to www.eastneukfestival.com. Kate Molleson talks to Llyr Williams at length in tomorrow's Sunday Herald.