It is more than a century since a Salzburg confectioner began manufacturing marzipan-centred, hazel-nougat-encased and chocolate-coated sweets, prettily wrapped in foil with an idealised image of the composer, called Mozartkugeln - or, more colloquially, Mozart Balls. Today you can buy the sickly things everywhere: almost wickedly appropriate tokens, it might be thought, for the figure the mythmakers and marketeers have gradually macerated over the two centuries since his death into the world's most consumable composer.
If concert promoters or commercial radio stations today want to mount a sure-fire classical summer festival that will attract the broadest of audiences (and, not incidentally, steal a march on a rival popular festival such as the BBC Proms), what do they put on? Basically Bach or Broadly Beethoven might be deemed a bit severe or strenuous for lazy July days; comparable festivals built round Brahms or Tchaikovsky rather too beefy or overwrought. But Mostly Mozart surely has it all: ease, style, accessibility and an absolute guarantee that, whatever the substance of the music, it is certain to sound unfailingly lovely.
And, beyond those qualities, there is all that eminently exploitable imagery - whether the rococo porcelain seraph or the demonic proto-Romantic amorist alternately favoured by the 19th century, or the post-Amadeus pop-star brat through whom the Almighty chose in his mysterious way to convey his sublimest inspirations. The world of Mozart scholarship, biography, musicology and criticism may continue to insist that his contemporaries saw him quite differently and that he himself had no such posthumous intimations; that much of his music can be explained according to the procedures of his time, and that some of his works are actually better than others. Yet nothing, it seems, will now dislodge the universal cliché of Mozart as the embodiment of so-called classical (the word "music" need no longer even be added).
Nevertheless, if only for the sake of sanity, what Adorno derided as "The Culture Industry" has to be challenged from time to time. For a start Mozart was by no means the all-time prodigy of popular myth. As a keyboard player, he was easily pipped to the post by the English infant phenomenon William Crotch, who gave his first public performance in 1778 at the age of two. And Saint-Saëns was already writing waltzes long before the five-year old Mozart played his first simple minuet to his father, who noted it down. To be sure, his progress over the next decade was formidable: rigorously drilled by the ambitious Leopold, admiringly tested at nine for the Royal Society in London, and coached in his early teens by the most learned contrapuntist in Italy.
Yet it can be argued that despite, or even because of, this training - to say nothing of the social advantages of having been dangled on half the royal knees in Europe - he was actually rather slow to find his true voice compared with successors such as Schubert or, especially, Mendelssohn. For all the intermittent pleasures of the first two hundred items in Koechel's catalogue, it is not until the Symphony in A, K201 - his 29th, composed at 18 - that we hear a mature Mozart symphony; and only with the Piano Concerto in E flat, K271, from his 22nd year, did he produce a work of undeniable genius.
What he was really doing as he scribbled those first 200 Ks was acquiring a sovereign command over all the standard genres, compositional procedures, even musical clichés of his day that would in due course enable him to fabricate, with a minimum of time and trouble, an adequate response to any musical demand made upon him. As a result, even the catalogue of his last dozen years, although teeming with masterpieces, is also interspersed with a great deal of pleasantly workaday stuff - hastily scribbled sets of ballroom dances and whatnot - which might scarcely attract attention by now were they not signed by Mozart.
The greatness of composers may be a matter of comparison, but we value a handful of geniuses - Bach, Beethoven, Schubert, Wagner, and so on - uniquely; so that if the achievement of any one of them was somehow expunged, we would feel it a hole in Western tradition, a loss of spiritual truth, even. Mozart was not really interested in, at least till comparatively late, the Baroque concept of the seamless melodic line; nor was he partial to the use of motifs in the manner of Haydn and Beethoven. His starting point was rather the galant principle of assembling melodies from contrasting units and forms by shuffling contrasted patches of material and texture, a technique partly learned from J C Bach and shared with such contemporaries as Salieri.
What lifted Mozart way above those contemporaries was his ability, through many internal parallelisms and links, to suggest that the particular order he had assembled his elements in was the right, the only, possible order to make full expressive and structural sense. Meanwhile these intermediate links were liable to be underlaid with still longer-term relationships of harmony and key; it was, indeed, this multi-level sense of structure most of all that enabled him to pull off the masterly spans of his last symphonies, the great quintets, and, above all, the huge designs of the three Da Ponte operas.
It was also the sense of musical layers working both in and out of sync that helped to generate the ever-shifting moods and complex ambiguities of feeling so special to his greatest music; it perplexed, even repulsed, many listeners in his own time, but has enabled every subsequent generation to hear and interpret him in a different way. In the light of this central achievement, the selling of Mozart on anecdotage of his miraculous childhood, getting kicked out by the Archbishop, pauper's grave and all the rest of it, is neither here nor there.
Admittedly, it would be expecting a bit much of a popular Mozart series not to climax with the Requiem. After all, it was supposedly ordered by a fatalistic Dark Stranger and posterity seems to have agreed that Mozart's contriving to expire amidst the scattered pages of its unfinished manuscript was his greatest career move. Yet, for the most part, the planners of the Barbican's upcoming Mostly Mozart festival, and Classic FM who are backing it, have rather admirably refrained from the more vulgar excesses of Mozart salesmanship - the short accompanying film series actually excludes Amadeus. True, the 12 concerts themselves also exclude the instrumental and chamber output - no great sonatas and fantasias, quartets and quintets - concentrating for the most part on a reasonably balanced choice from the orchestral, operatic and sacred music, interspersed with a sprinkling of complementary works by great contemporaries and successors such as Haydn, Beethoven, Schubert and Mendelssohn, and with such trivia as all those early Salzburg wind band serenades properly banished to the foyers where they belong.
Some of the programmes are positively enterprising: the recoupling of the 1786 double bill of Salieri's Prima la Musica poi la Parole and Mozart's The Impresario on 26 July should allow a genuinely musical rather than dubiously biographical comparison, for once. Indeed, the almost perverse choice of Mozart's rarely heard arrangement of Handel's Alexander's Feast to open the entire festival this Thursday should even bring the musicologists flocking. Most of the symphonies, concertos and so on are long-established standard repertoire, of course, but the choice of such younger artists as Magdalena Kozena, Paul Lewis and Jonathan Lemalu should bring fresh insights.
In short, a modest push in the right direction. More of the essential music; less of the Mozart Balls.
Mostly Mozart, Barbican, London EC2 (020-7638 8891) Thursday to 2 August