In late September 1835, 16-year-old Princess Victoria heard her favourite composer had died. "All true lovers of fine music (of which I am one of the greatest)," the future queen wrote in her diary, "must join in lamenting the loss of one whose compositions gave such delight." The "one" to whom she referred was Vincenzo Bellini, unexpectedly dead at the age of 34 at the moment when his operas were being staged throughout Europe.

Five years before, he had already announced to his lifelong friend Francesco Florimo: "my style is now heard in the most important theatres in the world . . . and is heard with the greatest enthusiasm". Today, Bellini's "style" is relatively little heard anywhere, and few of the 10 operas he composed remain in the general repertoire, even during the present year when the bicentenary of his birth - which falls tomorrow - has been overshadowed by the centenary of Verdi's death.

Vincenzo Bellini was born into a family of musicians in Catania, Sicily. Something of a child prodigy, by the age of five he could play the piano fluently and a year later produced his first composition. Having learnt everything possible at home, at 18 he went to study at the Naples music conservatory, where his remarkable talents were soon recognised.

At the end of the course, he was invited to present an opera to the public performed by his fellow pupils; this was Adelson e Salvini, which must be the only such work set in 17th century Ireland.

Bellini's principal Neapolitan teacher was an elderly composer, Nicola Zingarelli, who, contrary to popular opinion at the time, disapproved of Rossini, believing the latter's preference for florid ornamentation risked "destroying the true art of song". According to Florimo, Zingarelli told Bellini "the public wants melodies, melodies, always melodies . . . make it your study to set them out in the simplest way possible, and your success will be sure, you will be a composer".

The advice proved sound; a fundamental characteristic of Bellini's finest work is the presentation of pure and unadorned melody. In this, he appears to have benefited from a personal interest in southern Italian popular song. While it is impossible to quantify just how much such music influenced his own, seemingly, while still a student, Bellini compiled for himself an anthology of Sicilian verses from which "he was often humming and strumming".

During Bellini's relatively short adult life he rarely failed to meet public favour, although a couple of works - Zaira and Beatrice di Tenda - were poorly received. Tall, slender, blond and handsome, he embodied the male ideal of the period; the German poet Heinrich Heine, who was jealous of Bellini's social skills, later spitefully declared that "the whole man looked like a sigh in dancing pumps". But success was hardly dependent upon personal appearance or charm; Bellini achieved European renown because the music he wrote possessed qualities rarely, if ever, heard before.

From the start of his career, the young composer argued for the importance of melody as the best means of communicating with an audience. As a Milanese critic observed, his music "has the characteristics which are necessary to be effectively dramatic: simplicity, sweetness, vigour, passion". Bellini's writing is infused with what has been described as a "narcotic sensuousness", in which long vocal lines are supported by the simplest orchestration. Unlike other composers of the period, he minimised the differences between aria and recitative so that, thanks to sustained cantabile passages, it is frequently impossible to tell where one begins and the other ends.

Verdi considered Bellini's music "rich in feeling and in a melancholy entirely his own", remarking that even in the least-known operas "there are long, long, long melodies such as no one wrote before him".

The finest of these melodies, such as Amina's Ah non credea in La Sonnambula or Giulietta's Oh! quante volte from I Capuleti e I Montecchi, offer an elegiac simplicity unique to Bellini. In his memoirs, Berlioz, who was certainly not an admirer of the Italian composer, recalled attending a performance of I Capuleti in Florence in 1831, where towards the close of the first act, "I was carried away in spite of myself and applauded enthusiastically".

Exquisite as this long-breathed and unadorned music now sounds, its merits were sometimes initially better appreciated by the public than by performers. Many singers had become accustomed to treating an opera score simply as a vehicle for demonstrating their own elaborate vocal techniques. When Bellini revised his second opera, Bianca e Fernando, for presentation in Genoa in 1828, the principal soprano, Adelaide Tosi, insisted he alter her part because, she said, "it had no coloratura and was music written for children". The composer insisted he would not change a note "because I wanted my music to be performed, with the tempi established by me, and not at her whim".

The more simply his music was conveyed, according to Bellini, the more emotionally powerful its impact; ornamentation was unnecessary and unhelpful. As he told Carlo Pepoli, librettist of his final opera, I Puritani, "the music drama must make people weep, shudder, die by means of singing . . . poetry and music, to be effective, must be true to nature, and nothing else".

More than anything else, the aspiration to make audiences "weep, shudder, die" mark out Bellini as a composer, if not the composer, of the Romantic era. Even he could be swept away by his own work. At the premiΦre of Il Pirata, composed in 1827 for Milan's La Scala Theatre and taken from a play called Bertram, or the Castle of St Aldobrand by Irishman Charles Maturin, Bellini was so moved that "I was seized by convulsive weeping and could barely control it after five minutes".

Precisely because of this desire to engage the audience and take control of its emotions, Bellini paid greater attention to the libretto than had most of his predecessors. A reviewer of the first performance of La Straniera commented that the composer "always follows with his music the poetic phrases and the situations" of the libretto. As Wagner noted in 1880, "Bellini's music comes from the heart, and it is intimately bound up with the text".

From Il Pirata until his last opera, he worked with the same writer, Felice Romani, who was willing to tolerate exceptional demands; at the request of the composer, he rewrote the final cabaletta of La Sonnambula 10 times and the text of Casta Diva in Norma eight times. While working on the final scene of La Straniera, an exasperated Romani is said to have snapped: "For goodness's sake, what do you want?" To which Bellini replied: "I want something that is at the same time a prayer, an invocation, a threat, a delirium."

Achieving this ambition could never be easy, which helps to explain why Bellini's operas are now only intermittently staged. The sensibility of their plots belongs to an age quite different from our own, and furthermore they demand singers of superlative ability. Music critic Andrew Porter has written that anyone tackling the role of Norma, for example, would require "power, grace, pure fluent coloratura, tones both violent and tender, force and intensity of verbal declamation and a regal stage presence". Similarly, the 19th-century German soprano, Lilli Lehmann, who did essay this role, declared that Norma "should be sung and acted with fanatical consecration".

Unless performed with sufficient authority and conviction, Bellini heroines - in all his work the most important characters for whom he wrote the loveliest music - can risk seeming vapid and insubstantial. It is a great pity that there have been so few singers capable of bringing these scores to life. Ironically, owing to Bellini's powerful gift for melody, a more common fate for his music is that a handful of items have been plucked out of context and performed in concert hall isolation, contrary to the composer's belief in the dramatic unity of his work.

Bellini's "sublime simplicity of utterance" deserves to be savoured in its entirety.