WHEN MSTISLAV ROSTROPOVICH and his wife Galina Vishnevskaya were forced to emigrate from the Soviet Union 10 years ago, life in the West offered them unequal professional prospects. For Rostropovich, a famous cellist in his prime, emigration provided the chance to fulfill his dream of becoming a full-fledged conductor while maintaining his status as one of the world's premiere instrumental soloists. For Vishnevskaya, an equally famous star of the Bolshoi Opera, the possibilities were less inviting because her voice -- like that of every soprano in her mid-40s -- was past its peak.

Vishnevskaya has found another, equally impressive voice in her splendid autobiography. She is a born raconteuse as well as a born prima donna, and her book tells the story of what happens to great artists in a country where art is never free from political pressure.

The voice is unmistakeably her own (this is emphatically not an "as told to" biography), and her account is characterized by a fierce moral intelligence and unfailing eye for detail. From the tortured career of composer Dmitri Shostakovich to the systematic destruction of her and her husband's career in retaliation for Rostropovich's open support of Nobel prize-winning novelist Alexander Solzhenitsyn, Vishnevskaya pulls no punches.

Disdaining meaningless and misleading euphemisms like "conservative," she calls the Soviet cultural bureaucrats "swine." In 1948, the Party Central Committee issued a decree banning "formalism" in music and singling out Shostakovich and Sergei Prokofiev for special criticism. Vishnevskaya's description of Shostakovich's humiliation before his colleagues in the Moscow Conservatory is unforgettable.

"In February 1948 a general meeting was held in the Great Hall of the Moscow Conservatory -- one to which all of the prominent figures in the world of culture were officially invited. And in order to be given a lesson on 'the wrath of the people,' conservatory students were excused from classes and herded into the auditorium . . . One after another, the swine mounted the speaker's platform, as if in a major competition to smear people. In one day, all that Shostakovich and Prokofiev had ever created was destroyed. . . .

"In the auditorium, so jam-packed with people that there would have been no place for an apple to fall, Shostakovich sat alone in an empty row of seats. We have that custom: no one sits next to the victim. As in a public execution."

The attack on "formalism" in music was part of a larger campaign against "rootless cosmopolitanism" that affected every area of the arts and sciences and was directed most harshly at Jews. The campaign culminated in the "Doctors' Plot," in which Jewish physicians were accused of planning to poison Stalin, and ended before the doctors were executed only as a result of Stalin's fortuitous death in March 1953. During this period, Vishnevskaya notes, the usual obscenities on the Moscow subway were joined by new insults -- "Shut up, you rootless Cosmopolite" and, "Quit shoving, you damned Formalist!"

Vishnevskaya's own life offers enough material for a dozen operas or Russian novels. Born into an ordinary working- class family, she was raised by her grandmother near Kronstadt, the island naval fortress whose sailors played a crucial role in the Bolshevik Revolution of 1917 and in a bloody rebellion crushed by the Bolshevik government in 1921. Vishnevskaya's father, a Party official, played a role in putting down that rebellion.

In Leningrad, the teenaged Vishnevskaya lived through the "starvation winter" in which nearly 1 million died during the Nazi blockade. After the war, she had started singing in popular music halls when she began studying with a classical voice teacher. Those lessons were the only musical training she received before auditioning for the Bolshoi.

Between the war and her debut at the Bolshoi, though, Vishnevskaya had to fight another battle against tuberculosis. Doctors told her she would die if she did not have an operation to collapse her lung, but she refused -- literally jumped off the operating table as an enormous needle was being prepared -- because the procedure would have prevented her from singing again.

Near death and unable to eat, she was saved by -- here is another opera libretto -- an inexplicable urge to read Turgenev. "The blood rushed to my cheeks. With a pounding heart I accompanied the heroines of my favorite books -- faster, faster -- through the splendid, lush park of A Nest of Gentlefolk . . . And suddenly I wanted to get up. It couldn't be that I was going to die -- I was as young as the heroines of those books! . . . As of that moment, I began to fight for life."

After her recovery -- could there be any doubt that such a woman would recover? -- came acceptance at the Bolshoi, her debut in Beethoven's Fidelio and Tchaikovsky's Eugene Onegin, stardom, marriage to Rostropovich, the birth of two daughters, acclaim on the opera stages of New York, Milan and Paris.

Vishnevskaya's descriptions of how an opera singer prepares for new roles are fascinating and permanent additions to musical literature, and they are interspersed with domestic comedy of a higher order. Washingtonians who love Rostropovich as musical director of the National Symphony will love him even more as an over-zealous new father, making his baby sick on too much American-bought formula because he was horrified by his first glimpse of the bluish breast milk Galina had carefully expressed and stored in refrigerated bottles. "But she ate with such pleasure!" a crestfallen Rostropovich told the indignant Russian pediatrician.

Throughout, there is the counterpoint of tension produced by the political pressures to which no Soviet artist is immune. Vishnevskaya shows us the risks artist run when they fail to sign "routine" political denunciations; the humiliation of having to beg the authorities for permission to appear abroad; a distraught Rostropovich performing in London on the night the Soviets invaded Czechoslovakia in 1968; and, finally, the inexorable pressures brought to bear as a result of Rostropovich's support of Solzehnitsyn.

The authorities tolerated the fact that Solzhenitsyn was living at Rostropovich's dacha, but every door slammed shut in 1970 after the famed cellist took the unprecedented step of issuing an open letter in defense of his embattled friend. He compared the press campaign against Solzhenitsyn to attacks on Shostakovich and Prokofiev in the 1930s and '40s.

Both Rostropovich and Vishnevskaya became "un-persons," denied the right to perform in major concerts, thrown out of recording studios, facing empty halls because no notices had been posted of their prospective appearance. Finally, an exit visa was granted two weeks after a visiting Sen. Edward Kennedy (D-Mass.) personally interceded on Rostropovich's behalf with Leonid Brezhnev.

Vishnevskaya presents a final, heartbreaking portrait of her husband just before his departure, weeping after being told by a minor bureaucrat that he could not conduct an operetta in Moscow because "as a musician you've gone downhill."

The Soviet Union's loss of such artists is, of course, the West's gain. Vishnevskaya saw it all, remembers it all and explains it all in a voice as ringing and true as her most flawless high notes.