'DIAGHILEV: A LIFE' By Sjeng Scheijen, translated by Jane Hedley-Prole and S.J. Leinbach. Illustrated. 552 pages. Oxford University Press. $39.95.

When he died, at 57, Serge Pavlovich Diaghilev (1872-1929) was many things: the most celebrated of Russian emigres; the impresario of the Ballets Russes, the world's most famous ballet company; a pivotal figure in the recent histories of opera, stage design, visual arts, classical music, as well as theatrical dance; the hub of successive schools of artistic modernism; the man who had taken ballet from state patronage into the world of commercial sponsors; the most celebrated homosexual since Oscar Wilde.

He died in bed in Venice, Italy, in the Grand Hotel des Bains de Mer, on the Lido. The new biography by Sjeng Scheijen, "Diaghilev: A Life," does not, however, end there. Three weeks later his half-brother Valentin Diaghilev was executed in Solovki, the Soviet Union's first concentration camp. Serge's death made front-page news across the world. News of Valentin's death never reached his own children.

Previous biographies — this is the first in-depth volume since Richard Buckle's in 1979 — have said little or nothing of the family Diaghilev left behind in Russia. Scheijen, a Dutch expert in Russian art, demonstrates, however, that Diaghilev made repeated efforts to contact them. In late 1927 Serge became aware of Valentin's disappearance and prompted the French Foreign Ministry to apply its full weight on Valentin's behalf. Only when the Soviet authorities no longer feared any repercussions that Serge might have prompted did they proceed to have Valentin killed.

Diaghilev's early life had been Chekhovian: He grew up as a member of one of the most well-to-do families in Perm, the setting of "The Three Sisters," in the western part of Russia. Scheijen draws from the many letters he wrote to his cherished stepmother, in which we first feel Diaghilev's celebrated charm. But, in a stroke worthy of "The Cherry Orchard," Diaghilev's family life was shattered by bankruptcy in 1890, when his father's and uncles' estate had to be sold.

This bankruptcy is among Scheijen's many revelations. For fluency of storytelling, "Diaghilev: A Life" easily surpasses both Buckle's dense biography "Diaghilev" and Lynn Garafola's intellectual analysis "Diaghilev's Ballets Russes" (1989). Scheijen draws happily from a wide range of sources that have become available in recent years in Russia and the West, notably the diaries of the German diplomat and arts patron Count Harry Kessler and the archives of the composer Serge Prokofiev, both of whom were intimate members of Diaghilev's circle for many years.

Yet Buckle's approach — that of both celebrity hound and aesthete — and Garafola's probing application of modern historical methods both yield a far more intense wealth of detail. They also demonstrate a much greater sheer excitement over Diaghilev's achievements. The often cool Scheijen brings us the latest information but omits too many of the facts already in the common domain. And at many moments he prefers to concentrate on his archival discoveries rather than to re-examine central areas of Diaghilev's artistic work.

Ballet was not Diaghilev's first, second or third love. But he found in it the ideal vehicle to bring other arts together. It's also likely that it stimulated, and sublimated, his sexuality. As he developed a taste for younger men, so ballet brought him the male beauties he desired; and his status gave him maximum casting-couch power.

In several cases, his lovers — who included, successively, the star dancers Vaslav Nijinsky, Leonide Massine, Anton Doli and Serge Lifar — needed no seduction from him; they were ambitious. And this gay Pygmalion was most galvanized when he could turn these male Galateas into artists the world would worship. Ballet had hitherto been essentially a heterosexual art glorifying femininity, but now a long series of Diaghilev ballets cast more luster on hero than heroine, while at least two of them ("Jeux," "Les Biches") actively encouraged homosexual nuances.

Scheijen tackles this revealingly but calmly. At several points art and life for Diaghilev were indivisible. Notoriously possessive, he dismissed both Nijinsky (in 1913) and Massine (in 1921) from his company when first one, then the other, married. Then, in private, he broke down, both times. Scheijen shows that the loss of Massine — the more intelligent, worldly and self-sufficient, if less legendary, of the two — caused Diaghilev the greater crisis. He needed to be in love to keep working at his ferocious pace, but Scheijen's narrative implies that after Massine he was never again so passionately involved.

The book only skims Diaghilev's rediscovery of ballet classicism in his ill-fated decision to mount "The Sleeping Princess" (better known today as "The Sleeping Beauty"), the greatest of the 19th-century ballets originally choreographed by Marius Petipa. Diaghilev, who in 1900 had objected to Petipa as a leader of ballet's academic old guard, had come full circle by 1921; this ruinously expensive project was motored by his and Stravinsky's enthusiasm for what they now recognized as a masterpiece of classicism.

The exceptional ballerina Olga Spessivtseva was among the new blood Diaghilev transfused into that ballet's old framework. But once Scheijen has recorded that the "Sleeping Princess" was a fiasco (planned as a long-running blockbuster, it closed after only 107 performances, leaving Diaghilev with astronomical debts), he never mentions Petipa or Spessivtseva again. Nor does he relate that, according to Stravinsky, its disastrous first night caused Diaghilev another breakdown. You would not know from this narrative that, between 1922 and 1929, Diaghilev presented hundreds of successful performances of one-act excerpts from choreography attributed to Petipa. He programmed these alongside his modern repertory, revitalizing ballet by showing the connections between past and present.

Diaghilev's mixed feelings for George Balanchine get short shrift too.

Balanchine was always grateful (other sources reveal) for the artistic education Diaghilev gave him, and the two men enjoyed talking. Yet Diaghilev felt more detached than he had been with those choreographers he had both bedded and molded; Balanchine was heterosexual, independent and remarkably proficient.

Even so, Diaghilev took more pleasure in the young man's masterpiece "Apollon Musagete" (1928, known today as "Apollo") than Scheijen does. "What he is doing is magnificent," Diaghilev commented on "Apollo" in rehearsal. "It is pure classicism, such as we have not seen since Petipa's."

Scheijen's biography, while it is an important addition to the large shelf of Diaghilev literature, cannot stand as the definitive one. It's a tribute to Diaghilev's Protean diversity that no biography of him fully satisfies.