Of the Three Tenors, he is the most famous, and the only Italian. Although Placido Domingo is the more intellectually powerful, and Jose Carreras the more innately musical, Luciano Pavarotti has always had the edge. The voice itself, filled with all the powerful contradictions of a great actor -- suggesting power and vulnerability at the same time -- gave him precedence. It was an extraordinary gift, a gift he marshaled, and a gift that has made him one of only a handful of opera stars to become a household name in the last century.

When people who hate opera make exceptions, it is always for Pavarotti. They may not remember or care very much for what he sang, but they remember the smile, the cheerful mugging, the odd grace of a very large man at home on the stage. Or perhaps it's the trademark white handkerchief, draped through one hand, suggesting again a contradiction: a touch of dandyism, or a security blanket? Perhaps it's both.

This year marks the 40th year of his career, a remarkable achievement for any tenor. Even more remarkable has been the consistency. A recording of Pavarotti made five years ago sounds not that different from a recording of Pavarotti made 30 years ago. He may have been a little callow in the very beginning, when the voice wasn't always comfortable stratospherically, and he may show a little strain more recently; but in between there has been an unbroken golden stream of sound, with clean, clear diction and a flawless, liquid line.

"I am a Libra," he offers as an explanation. Speaking from the New York apartment where he lives during his frequent appearances at the Metropolitan Opera, Pavarotti is as usual: genially condescending to interviews. If there's irony behind his sometimes weirdly enigmatic answers, it's lost in translation from his native Italian to his peculiarly childlike English.

"Libras have a sense of measure," he says. "They know what is good and bad. They have doubts. I am always conscious of what my voice can do."

Pavarotti began where so many tenors begin, with the lyrical purity of Rodolfo, the young bohemian lover from Puccini's "La Boheme," the role he describes as "my first love, my debut." That was 1961, when the tenor was an unknown young aspirant in Italy.

Five years later he sang a role that would establish him in the annals of operatic history: Tonio, a relatively small part with some extraordinary althletic challenges in Donizetti's "La Fille du Regiment." There is an aria in that opera which asks the tenor to take a high C nine times in succession. The average tenor would sing the top note with an easily manageable light falsetto voice. Pavarotti took it with his full voice, nailing it nine times in a row with thrilling ping and punch. It made him a legend, all the more so when he repeated it with even more success in 1972 at New York's Metropolitan Opera. They called him King of the High C's, a name that took with audiences even if the real beauty of his voice was not at the very top.

"That was a very big challenge but it was a very beautiful success," he says. "It was very unusual -- I was the first -- for a lyric tenor to sing all those notes in full voice."

The United States has been central to Pavarotti's career, where he has become two artists. The one most people know now is the stadium singer, the crosser of boundaries, the Pavarotti who sings with pop stars, who has turned "Nessun dorma," the tenor showpiece from Puccini's "Turandot," into something like a popular anthem.

The impact of his use of popular music marketing in the realm of classical music has been staggering. When Pavarotti teamed up with Domingo and Carreras to launch the Three Tenors concerts in 1990, it helped spell doom for an earlier era of classical music. A genial gentlemen's business of low profits and high idealism came crashing down. The large corporations that bought up the major record labels realized -- almost entirely through Pavarotti's example -- that there were huge profits to be made. And the business rapidly skewed toward a handful of megastars who could carry the bonanza projects.

Pavarotti made a fortune as he redirected his career away from the hard work and relatively low pay of the opera house, and toward the eye-popping record crowds of concerts in London's Hyde Park (250,000 gathered in 1991) and New York's Central Park (half a million in 1993). The Three Tenors became an industry, and for a while it was unstoppable. In 1998 their Paris installment was televised -- to 2 billion viewers. It has moved to smaller venues in recent years, and the stadiums have not always been full. There have been complaints, as there were two months ago in New Mexico, that top-ticket buyers who paid a premium for the best seats and dinner with the star got no more than a grunt and a stern warning to make no personal approach to the man.

"I don't know about the Three Tenors," he says today. "We take it day after day. If something good is coming, we will do it. Otherwise there is no reason."

The other Pavarotti, the singer who continued with the thread of artistry that began 40 years ago, is known to only a relative handful of people. Pavarotti has never stopped appearing in the opera house, even as his weight made it difficult for him to play the boyish roles at which he excelled. But he would occasionally experiment. In 1993 he sang the decidedly obscure Verdi opera "I Lombardi" at the Met, a role that had been out of his repertoire for almost a quarter-century. He undertook the heavier tenor role of Verdi's Otello in a concert performance at Carnegie Hall, a role that critics feared might destroy his voice. He knew his voice well enough to take the odd risk.

The Met remained a home for Pavarotti, honoring him with coveted opening-night appearances and regular gala celebrations on major anniversaries. It would do almost anything for him. When he was cast as Nemorino in Donizetti's "L'elisir d'amore," despite a hip problem that limited his ability to do much more than walk a few paces and stand a few minutes, the Met accommodated him with a production designed around his infirmities. He retains a special affection for the company, especially for James Levine, its music director.

"In this place we do something very extraordinary, something very important for opera," Pavarotti says, recalling his appearance as Rodolfo on the first "Live From the Met" opera telecast in 1977. "Television was extremely important. I was nervous, like always."

Like always?

"Always nervous. For me to sing for 10 people, or to sing for 10 million, or a billion -- like we have done -- doesn't mean much. You have to sing the same way, you have to serve the composer every time."

Pavarotti's voice is a classically proportioned lyrical tenor, and his ideal roles form the core of the dashing leading-man repertory. He was one of the best ever in the role of the Duke in Verdi's "Rigoletto"; the Calaf he sang opposite Joan Sutherland's "Turandot" on the legendary Decca recording is unmatched for tonal beauty; and his Rodolfo recorded with Herbert von Karajan in 1972 is a benchmark.

But among critics and serious opera lovers, there is another role, from a Mozart opera, that is, in retrospect, heartbreaking. In 1964, he sang Idamante from Mozart's then little-known "Idomeneo" at Glyndebourne, England. It was a serious role, by a serious composer, sung for one of the world's smallest but most serious opera audiences. And it was said to be spectacular. From that role he moved on to the larger title role of the opera, numbered among his greatest, if least appreciated, successes. A recording made years later confirmed his power in Mozart. Domingo, the thinking tenor, has subsequently taken up the role, but Pavarotti got there first.

Pavarotti has had to fight the reputation of being a spoiled Italian tenor his whole career -- the strange superstitions, the exorbitant financial demands, the finicky dressing-room food requests, and recently a punishing fight with the Italian tax man (last year he paid $11 million in back taxes and in October was acquitted of charges of tax fraud). But his Idomeneo is of different cloth: pure, noble, exalted in expression.

Pavarotti the musical colossus has always been shadowed by his own soul, the childlike and idealistic love of music that has never entirely fled, even under the stare of the television cameras and the glare of the stadium floodlights. And that soul sounds like this, like Mozart, resplendent with Mediterranean sun and a sense that song is inevitable, necessary, of the blood and in the genes. To summarize the man and his career, you can say he changed the world of classical music, for better and worse; to summarize his artistry, you can say that he once sang Mozart beautifully.

Showing his range: Luciano Pavarotti in "Aida" at the Met earlier this year, above; drawing a crowd in Paris with the Three Tenors in '98, right; and in the Met's "L'Elisir d'Amore" in '84.