By Michael Walsh

"God knows, I should be dead by now," Leonard Bernstein remarked a couple of years ago. "I smoke. I drink. I stay up all night. I'm overcommitted on all fronts. I was told that if I didn't stop smoking, I'd be dead at 35. Well, I beat the rap." In fact, ever since Bernstein leaped to fame nearly five decades ago, he lived his life the way he composed and conducted: passionately and wholeheartedly, as an outsize, outrageous combination of creative joie de vivre and destructive self-indulgence. His death last week at 72 has left the music world a quiet place.

Just how seriously ill Bernstein was--he was suffering from emphysema and a pleural tumor--became clear two weeks ago, when he announced he was retiring from conducting; conductors don't retire, they die. Even so, his death came as a shock, for at times he did seem invulnerable to mortal wear and tear and fearless of the consequences. When the gods have so lavishly blessed you, why worry?

Conductor, pianist, composer, teacher, television host and celebrity, Bernstein was the signal musical figure of his age, at once the best, the brightest and the most exasperating. Born to Russian-Jewish immigrants in Lawrence, Mass., Lenny, as he was universally known, attended the prestigious Boston Latin School and Harvard. His formidable father Samuel ran a profitable beauty-supply business and for many years bitterly opposed his son's choice of career, although late in his life he admitted, "You don't expect your child to be a Moses, a Maimonides or a Leonard Bernstein."

In 1943 conductor Artur Rodzinski named Bernstein his assistant at the New York Philharmonic: "I finally asked God whom I should take and God said, `Take Bernstein.'" God was right. Three months later, Bernstein substituted at the last minute for an ailing guest conductor, Bruno Walter. His debut, broadcast live across the country on radio, was front-page news in the New York Times and made him an overnight sensation.

Throughout his career, the words first, American and conductor seemed to be inextricably linked to his accomplishments. He was the first American to conduct at La Scala (1953). When he took over the New York Philharmonic in 1958, he was the first native-born American to be named music director of a major American orchestra. He was the first conductor to take the Philharmonic to South America, Israel, Japan and the Soviet Union. During his tenure, which lasted until 1969, the Philharmonic enjoyed a golden age, selling millions of recordings and holding a status among American ensembles it has never recaptured. A peerless spokesman for his art, Bernstein also imaginatively entertained and instructed a nation with his Omnibus and Young People's Concerts television broadcasts in the 1950s and '60s.

On the podium, Bernstein was a figure of uninhibited emotional energy. Through exaggerated gestures that would have done Barrymore proud, he cajoled his orchestra. He pleaded. He commanded. He looked heavenward for inspiration. At times he would even levitate, jumping into the air as if to transcend the forces that kept him earthbound. When such dramatics worked, the results were stunning: Haydn that crackled, Mahler that mourned, Beethoven that shouted in triumph. But when they didn't, which was almost as often, his performances were vulgar and mannered, seeming to reflect the man portrayed in Joan Peyser's controversial 1987 tell-all biography.

Many of Bernstein's admirers believed his real vocation was composer, not conductor. Yet the brilliant scores on which his reputation will rest predate his ascendancy to the Philharmonic: the ballet Fancy Free, choreographed by Jerome Robbins, which later evolved into the Comden and Green musical On the Town; the Symphony No. 2, subtitled "The Age of Anxiety"; the one-act opera Trouble in Tahiti; Candide, a kind of Broadway operetta; and his masterpiece, West Side Story (with lyrics by Stephen Sondheim), completed in 1957 and still the greatest music-theater piece written by an American.

Thereafter, as Bernstein became more immersed in conducting, his compositions suffered. It seemed to embarrass him that his best works were in a popular idiom, and he sought to burnish his "serious" credentials with such efforts as the earnest but awkward "Kaddish" Symphony of 1963, the bathetic Mass, which opened the Kennedy Center in 1971 and, most disastrously, the opera A Quiet Place (1983), which was intended as a sequel to Trouble in Tahiti but succeeded only in spoiling its memory. (A Quiet Place was, however, the first American opera performed at La Scala.) Bernstein even lost his touch on Broadway when his 1976 musical 1600 Pennsylvania Avenue closed after just seven performances.

With Bernstein, it was always hard to separate the man from the showman. His commitment to liberal causes was neatly skewered by Tom Wolfe in Radical Chic. Yet when the Berlin Wall fell, Bernstein was on the scene quickly, leading heroic performances of Beethoven's Ninth and characteristically substituting the word Freiheit (freedom) for Freude (joy) in the choral finale. He reveled in his private life as a homosexual, yet his marriage to Felicia Montealegre Cohn lasted until her death in 1978 and produced three children.

"The talent that was once a genius," went an oft-repeated verdict on Richard Strauss, alluding to his long creative decline later in life. The same might well be said of Bernstein. His tragedy was that he had too many talents and not quite enough genius. He wanted to be not Moses or Maimonides but Mahler; he had to settle in the end for being Leonard Bernstein. But that in itself was a dazzling achievement.