MUSIC / When two minds meet: Sviatoslav Richter has raised unpredictability to an art. But when he's good, he's great. Stephen Johnson reports on the 21-CD 'authorised' edition

Once you get above a certain level in the musical career stakes, unpredictability can be a major asset. There's nothing that raises the tension at the start of a potentially outstanding concert more than an element of doubt - will the great performer deign to appear at all? The Russian pianist Sviatoslav Richter has refined this art to a degree no other musician - not even in the opera house - can quite match.

I remember the excited murmur that ran round the Amsterdam Concertgebouw auditorium one June evening in 1986 as Richter appeared, descended the stairs and seated himself carefully at the piano. Was he actually going to play?

After that the unforeseeables multiply. Will the house lights dip so low you can hardly see your programme, let alone read it, as at last year's Barbican concerts? Or will there be other enigmas: the piano lid firmly down for a barely audible Bach sequence, then flung wide open for a Beethoven sonata that seems addressed to the whole world, not just one tiny concert hall? London has seen that too.

But in Richter: The Authorised Recordings, a 21-CD set from Philips Classics of mixed concert and studio recordings (many not previously released), the attention is focused on the music-making and nothing else. One overriding impression is that, no matter how volatile, brilliant, dramatic or downright bizarre Richter's playing, one quality it is quite free from is vulgar showmanship. You may question some of his artistic decisions, but they are almost always the result of serious consideration. The first movement of Schubert's G major Sonata, D 894, is breathtakingly slow - the opening hardly seems to move at all. Richter's argument is that Schubert's marking, Molto moderato, refers to the quaver beat, not the dotted crotchet. In pure musicological terms, I don't imagine many Schubertians will be convinced, yet somehow Richter's concentrated, intensely absorbed playing persuaded me to suspend disbelief. Even the weird decision to repeat exposition and introduction in the Beethoven Quintet for piano and wind, Op 16, has a kind of perverse justification. This time it doesn't come off, and yet the playing is so vital, with such joyously spontaneous give and take between the piano and the four wind soloists, that it's tempting to forget those tiresome structural signposts and enjoy - well, almost.

However alive and sharply intelligent the playing, it would be wrong to claim that Richter is equally at home with all the composers included here. His Chopin, for instance, has always been controversial, not because he brings startling new readings, but because of an untypical blurring of the artistic focus. Richter has admitted that he finds the classical and romantic tendencies in Chopin difficult to balance, and you can feel it in the way the playing seems passionately involved one moment, unrelenting or withdrawn the next.

But along with Chopin in that three-CD sub-set is a disc and a half of some of the most riveting Liszt playing I can remember. The prophet, the fantasist and the romantic visionary are all there, this time well-balanced. Liszt can so easily come over as an empty exhibitionist - 'tawdry and swaggering', as Neville Cardus put it. But in some of the short pieces, and especially in the Sonata, Richter finds an inner continuity, almost - if not quite - as compelling as in Beethoven or Schubert.

Listeners who enjoy pouncing on minute blemishes would no doubt have a rapturous time here. Quite a few of the live performances have their wrong notes, sometimes in thunderous fistfuls, and there are other moments where - to borrow an image from Browning - Richter's reach seems momentarily to have exceeded his grasp (though his technical grasp remains formidable). All this confirms to me is that here is a performer who is not afraid to take risks, who even revels in them. I'm reminded of Artur Schnabel's reply to a conductor who asked if he wanted to re- record a gloriously fudged passage in the Brahms First Piano Concerto - did he think he could do it better? 'It might be better,' replied Schnabel, 'but it could never be as good.'

This risk-taking is one facet of a larger phenomenon - perhaps the essence of Richter's Beethoven, Schubert, Liszt and Prokofiev. 'Spontaneity' somehow doesn't seem a big enough term to describe it. In tiny details as much as in grand gestures, he can give the impression that the music is not merely being played but created before your ears. Richter doesn't approach Beethoven as a monument, to be treated with a certain reverent distance; in places it's as though you were listening to one of the composer's own improvisations. The climactic sforzando in the opening bars of the Sonata in E flat, Op 31 No 3, is so perfectly judged it sounds as if it had only just occurred to him - a momentary inspiration.

For Richter at his greatest, a performance is not a one-man show but a meeting of two minds, composer and performer. Horowitz is Horowitz, whatever he plays. Richter's Mozart feels a long way from his Beethoven, or even his Haydn. In the latter one feels something of the Beethovenian volatility and intellectual brilliance, but combined with telling sensitivity and delicacy - a lighter touch.

His Mozart is no Dresden figurine, especially not in the great C minor Sonata and Fantasia, but at the same time one feels that this is a performer who knows his Austrian rococo. From that to the German High Baroque of Bach is more than a step or two. Purists would no doubt balk at some of Richter's tempos, especially in so- called 'slow' movements - if they allow Bach on the piano at all, that is. Those who persist will find playing that seems well aware of how the harpsichord colours and textures Bach, but which is able to translate that insight into purely pianistic terms. And there can't be many harpsichords that could sing the central aria from the Italian Concerto so freely, eloquently and stylishly.

Obviously Richter: The Authorised Recordings is aimed at those with above average credit-ratings, though the nine individual boxes within the set will be issued separately in October. When they are, I hope the booklets manage to squeeze in more information about which recordings are live and which studio-made. Not that it makes a great deal of difference to the quality of playing. In one or two of the studio recordings the manner seems more thoughtful, less spontaneous, and yet there can be glorious things there too. The selection from Shostakovich's 24 Preludes and Fugues has a special absorption, an inwardness in the quieter numbers that again I have never heard equalled - and the sustained tremolo in the E flat minor Prelude is a pianistic miracle. If only he'd recorded the whole cycle. Acquiring the nine sub-sets (two or three CDs apiece) may be a more attractive proposition, but I wouldn't be without any of them. To those who complain wistfully that the age of great pianism is long past, this Philips set is an emphatic denial.

(Photograph omitted)