The greatest pianist of his generation?

To watch Evgeny Kissin in concert is to understand the old equation between musical genius and the devil. In a word, it's frightening. You could easily believe this man/boy - 24 years old but with the features of a pre-pubescent serial killer - had a simple choice: become the greatest pianist of his generation or end up in prison. And no one who heard the 3rd Rachmaninov Concerto he played at Barbican on Wednesday could doubt that he is the greatest pianist of his generation, if not several others besides. It was deliberate, epic, making every note tell (in a piece where every third note usually gets fudged), and as a consequence a bit slow: over-indulged, maybe, by the old-school Russian conductor Yevgeny Svetlanov, who mothered a wonderful sound from the Philharmonia, but doesn't so much beat time as swim in it. No stick, just wafting hands that hold the music like a vodka bottle, lovingly if rather hazily.

The audience went wild with adulation on a scale not witnessed at the Barbican for many months, and rightly so: it was a staggering performance. But disturbing too. The genius of Kissin isn't comfortable: it threatens with excess - not in the crazily eccentric manner of an Olli Mustonen, but with the sheer alien otherness of its uncompromising stature. Everything is too much - from the clammily impasted legato he achieves with sensual, almost sexual, hand movements, to the way he sits high over the keyboard and hammers the leggiero marking with his total upper-body weight. Certainly, this was the most impressive concert I've been to all year; but for enjoyment, I heard better ways to handle warhorse repertory elsewhere this week. In Bergen.

Bergen is a small, scenic city on the west coast of Norway, famous for rain, fish, and Edvard Grieg - who said in one of his periodic moments of self-doubt that he was sure his music had a taste of cod about it. Grieg is to Bergen what Shakespeare is to Stratford-on-Avon. His leonine but worried profile stares out from shop windows and down from the plinths of civic statuary. His house in the Bergen suburbs is Norway's principal tourist attraction after the fjords. The city centre's proudest building is the Grieg Hall, home to the Bergen Philharmonic, who still live off the performance rights left them in the composer's will. And "GRIEG" shines across the harbour, in large neon-lit letters which, on investigation, turn out to be promoting a shipping company of the same name, but no matter.

It accordingly comes as no surprise that Grieg underpins the Bergen Festival, whose 44th edition has dominated Norway's cultural life in the past few weeks. It's a sprawling international event which this year, as always, sucked in a good number of touring Brits including the Royal Ballet and Paul McCreesh's Gabrieli Ensemble. But for a foreign visitor, the chance to hear some ostensibly authentic Grieg on home territory is the big attraction - and beyond that, the chance to hear him in context. Grieg may be the only household-name composer Norway has produced, but that doesn't make him an entirely isolated phenomenon. He came from and fed into a continuing tradition that owes its soul if not its technique to folk melody: the escape from Austro-German domination pursued by so many emergent musical cultures in the late 19th century, not least our own. The extent of Grieg's debt to folk music is arguable - he was, after all, conservatory-trained in Leipzig - but the essential fact of it is not. You hear the dues in his chromatic vagaries, his heavy rhythms and his embryonic wildness. Ninety-odd years and several Hollywood rewrites since his death, we tend to hear Grieg as a confectioner of tame, salonised bon-bons; and yes, essentially he was a miniaturist. But there was a rough-edged daring in his make-up, and an inclination towards "innocent" experiment that, alas, wasn't often followed through but can be felt as a potential in the music.

For me, the best things in the Bergen Festival were two remarkable performances where that potential was upfront. One came from a truly outstanding and very young Norwegian duo - violinist Henning Kraggerud and pianist Helge Kjekshus - who turned up in the middle of a draining all-day concert marathon at the Grieg Hall with a reading of the 2nd Grieg Violin Sonata that perfectly caught its tension between salon refinement and raw, vernacular excitement. The other came from a young pianist, Havard Gimse, whose Grieg A Minor Concerto I was no more looking forward to than I would any account of the Grieg A Minor Concerto. But the Bergen Philharmonic turned out to be rather good - no doubt they know the piece - and Gimse was downright magnificent, with a fierce, wiry intelligence that challenged the old war-horse out of all its cliches: freshly, glacially Nordic as opposed to sentimental MGM Victorian.

That said, there is a fair amount of Victorian kitsch in Norwegian folk culture, and we weren't spared it at Bergen. Some days you couldn't move for people in national dress playing the Hardanger Fiddle: a loud instrument whose eight strings - four for playing, four for resonating underneath them, to enrich the tone - are accompanied by a stamp of the foot on every other beat. Norwegian composers have been trying to corral the Hardanger genre into conventional concert music ever since Norwegian composition began, the first notable example being Ole Bull, the Paganini of the North and Mr Fixit of 19th-century Norwegian culture who, in between founding the National Theatre, discovering Ibsen and Grieg, and tossing off feats of violinistic virtuosity before crowned heads of Europe, found time to write quantities of vernacular-inspired salon scores. I heard some of it at a recital in Ole Bull's own house near Bergen (now a museum), played by the latterday Nordic virtuoso Arve Tellefson, and it was lacy bric-a-brac. I also heard, in the Festival's closing concert, an attempt at a concerto for Hardanger Fiddle and symphony orchestra which didn't work (the clash of cultures was too great) and an orchestral score, Carmel Eulogies, by Lasse Thoresen, the Festival's featured living composer, which handled the folk-tradition issue in a more absorbed, conceptual way and worked very well. Unknown in Britain, Thoresen is a name to listen out for.

But the unknown Norwegian name I guarantee British audiences will be listening out for a year from now is Harald Sverud, whose centenary in 1997 (he died four years ago) is about to be sold by the Norwegian government with some vigour. Sverud was many things that Grieg was not: a symphonist, a neoclassicist, an embryonic Nordic Hindemith with an echt- Hindemithian inclination to banality. But like Grieg, he produced a quantum of piano music which translates Norwegian folk vernacular into cultivated art: in Sverud's case a kind of early minimalism that relies on simple, endlessly repeating motifs spiced by wrong-note harmonies. I heard a whole programme of these pieces in a concert at Sverud's old home, another wooden house in the Bergen hinterland; and although they half-irritated me at the time, I haven't been able to forget them - especially a piece called Ballad of Revolt which works on the same principle of accumulative power through repetition as Ravel's Bolero. Sverud has populist potential. Maybe next year it will come to something.