How music lives and grows

Ah, the suggestive power of an unwished-for nickname! Eventually, even Beethoven himself became impatient with the popularity of the work he published in 1801 as Sonata quasi una fantasia, Op 27 No 2: "Everyone goes on about the C-sharp minor sonata! Surely I have written better things?" All too soon, it seems, and all too pervasively, the opening Adagio of the so-called Moonlight sonata threatened to degenerate into the kitsch evocation of "romance" it is too often heard as today.

Yet, listen again – or better still, attempt, however haltingly, to fumble it through at the piano. Beethoven's indication that the Adagio should swim continuously in pedal-resonance was, itself, more or less unprecedented – even if this has to be modified somewhat on the more reverberant modern piano. Equally novel, if founded in an 18th-century preluding tradition running back to Bach, is the form of the Adagio: neither freely improvisatory, nor a strict sonata form, but a kind of dissolved sonata, in which the bass line is more sustained than the curiously intermittent melody it supposedly supports, while the true focus often shifts to the continuous, ostensibly accompanying triplets.

Here, well before John Field or Chopin, is surely the true source of the 19th-century nocturne tradition. But no 19th-century Romantic would have dared to shatter the crepuscular trance of the Adagio with the crisply classical little Allegretto with trio that Beethoven brings in attacca – nor immediately overwhelm that, in turn, with the tumultuous and fully-worked-out presto agitato sonata structure that forms the finale, radically overturning, in the process, the 18th-century tradition of placing the structural weight of a sonata in its first movement rather than its last.

Atmosphere, humour, drama: it is the extremity of the contrasts in feeling, character and technique the 31-year-old composer somehow contrived to integrate into a work lasting little more than a quarter of an hour that is most striking of all.

But then, more than the symphonies, more even than the string quartets, it is the sequence of 32 piano sonatas that surely offers the most nearly comprehensive view of Beethoven's entire musical development. For a start, at least 10 of them were composed before 1800, the year in which he published his still relatively contained First Symphony and Haydnesque first set of quartets, Op 18. In the three sonatas, Op 2, which he composed at 24, we hear not only the dazzling brilliance of the young virtuoso, but the unpredictable humour and laconic force of his emergent personality, while, in the Sonata, Op 7, composed only two years later, he is already elaborating his forms with a breadth to match the longest of the later sonatas.

Nor were the heroic years of 1800-12, into which he packed his first eight symphonies and 11 quartets, any less prodigal of piano sonatas, with the utterly different Waldstein and Appassionata being just two of the increasingly idiosyncratic dozen he produced during this period. Granted, only two sonatas date from the difficult years of 1813-17 when Beethoven was beset with personal problems, but it was with the grandest of them all, the Hammerklavier, completed in 1818, that he inaugurated what was to prove his final period. And although he renounced piano composition in 1823 as no longer adequate to his expressive needs, his last three sonatas of 1820-22 are complementary in their vision and depth to the late string quartets of his remaining three years.

Even if the piano sonatas of Haydn and Mozart had not fallen out of fashion, and those of Schubert gone largely unpublished for years, Beethoven's comprehensive achievement would surely have dominated the 19th-century piano repertoire. This is not only because of the remarkable way in which his increasing technical demands anticipated, even forced, the development of the instrument itself, but because the 32 sonatas offered such a range of rewards for players from the modestly aspiring amateur to the most transcendentally brilliant professional. And, while professionals such as Liszt rampaged round the recital halls with the Hammerklavier, it was the hundreds of thousands of amateurs all across Europe in the era before the gramophone, earnestly attempting to master and make something of such sonatas as the Pathétique on their parlour pianos, who really confirmed the lasting centrality of the Beethoven canon.

Still a potent consideration in recital planning – look at the Wigmore Hall bill for any week – the sonatas have accumulated a commensurately rich literature from scholars and performers from Schenker to Brendel. And now, from the most consistently readable pianist-writer of the last 40 years, comes Beethoven's Piano Sonatas: A Short Companion by Charles Rosen. Based on a series of lecture-concerts at an Italian festival, this, admittedly, is a rather different book from his previous masterpieces The Classical Style and The Romantic Generation. Where the synoptic concerns of those volumes enabled him to home in on the music that really engaged him, one occasionally senses that he finds working systematically through a complete catalogue less congenial.

Compared with the bar-by-bar parsing of Tovey's time-honoured Companion to Beethoven's Pianoforte Sonatas, published in 1935, Rosen's chronological commentary, which comprises the second half of his book, is more lapidary in its illuminations, and occasionally falls into sketchy description or mere key-naming. It is the first half that most consistently fulfils his aim of "a practical book, meant as a guide for listeners and performers to many aspects of the Beethoven piano sonatas not always well understood today". Here he discusses, successively, the formal principles behind Beethoven's musical thought; questions of phrasing and tempo – this chapter is especially detailed and salutary; and Beethoven's use of the pedal, trills and the limits of the keyboards he knew. Rosen illustrates many of the points he makes on an accompanying CD, if with somewhat casual pianism.

But Rosen's most valuable implication here is his recurrent sense of the sonatas as the epicentre for the ever-changing thoughts, feelings and practices of musical amateurs and professionals alike over the two centuries from Beethoven's time to our own. And in this, the book links up with a substantial essay he published last December in the New York Review of Books, entitled, a little misleadingly, "The Future of Music", but actually concerned with the heritage and prospects of classical performance. Observing that "the distinction between idea and realisation is built into Western cultural history," Rosen suggested it was the very incompleteness of European music's unique system of notation that ensured its lasting vitality, in that performers were compelled to add something of their own to every realisation of a score. By this means, the most remarkable works escaped the original conditions of their time and place, acquiring a permanent "greatness" beyond the encompassing of any single performance.

However, this living evolution, he argued, is now threatened, not only by "authenticists" who seek to reinstate those original conditions, but, more radically, by recording, which substitutes for the active tensions of realisation, a perfect sound image that reduces involvement to mere passive consumption. Thus, while the Beethoven sonatas would always survive as cultural documents, Rosen envisaged a time when their style of performance might have to be consciously reinvented, much as early-music scholars have had to find ways of performing the documents of long-lost medieval traditions. Rosen is not against period-performance information, imaginatively reinterpreted. Nonetheless, his Beethoven companion is a powerful argument for the richly inauthentic virtues of a continuing live tradition.

'Beethoven's Piano Sonatas: A Short Companion', by Charles Rosen, 256pp plus CD, £20, is published by Yale on 7 February