"A MIGHTY FORTRESS," THE Marseillaise, "Va pensiero," "We Shall overcome; a song can be a symbol as potent as a flag. A singer can become a symbol, too. It happenecl to Marian Anderson, the black contralto from Philadelphia, whose eloquence and calm dignity stood in the minds of millions around the globe as a blazing indictment of racism in America.

Now, for another reason, an aura of heroism surrounds the Spanish tenor José Carreras, who returns to New York for a recital at Carnegie Hall on Tuesday. He has survived leukemia.

His own thoughts are mostly on other things. In a recent telephone conversation from Seville, where he was appearing at the new Teatro de la Maestranza in "Carmen," Mr. Carreras said: "In the beginning, you, think your life will change completely, You think that if you live, you will act in a very wise and intelligent way. Then, slowly, slowly, because you're feeling fine, and involved again in what life has to offer, you go back and make some of the same mistakes you made before. You think more with your heart than with your brain. Life is normal again."

There is strange comfort to be had in another person's brush with death; it almost awakens a hope for a little temporary immortality. When performers come back, the hope seems brightest. Their art makes them look so alive. But few come back.

Sean Lavery, the unforgotten, golden Apollo of Balanchine's last years, came through surgery for removal of a spinal tumor that turned out to be benign. Today he serves as New York City Ballet's assistant to the ballet master, orchestrating, among other things, the Dancers' Emergency Fund benefit that closes each winter season. For all his, courage and physical therapy, he has not danced again. It is a wonder he can walk.

Right now, after: the removal of a malignancy in her brain, the beloved soprano Arleen Auger is undergoing radiation treatment. Her name, meanwhile, still appears on the concert schedules for the coming season, and every music lover must hope that she will be able to fulfill her engagements at her accustomed standard.

Five years ago, Mr. Carreras, then 41, was merely one of the opera world's three best-paid and most adulated tenors. In his 20's he had emerged as the, possessor of a lyric instrument of great I allure and refinement. His acting combined thoughtfulness with intensity. By 1987, the tight vibrato of his early years had loosened, and his high C was unreliable, but then, it always had been unreliable. He was working in the great houses in heavy tenor roles in operas like "Turandot," "La Forza del Destino," "Aida" and "Carmen."

Critics worried about, him. Some said the bloom of his youth was going. Others said it was gone, But there was no decline in the demand for his services.

Had his career ended then, it would already have been considerable. Born into a nonmusical Barcelona family in modest circumstances, he made a precocious radio debut at the age of 7, singing 'La donna è mobile" in a fiery boyish mezzo-soprano. At 10, he appeared as the boy at the Gran Teatre del Liceu in Manuel de Falla's "Retablo de Maese Pedro," a challenging part usually entrusted to an adult soprano. At 24, he was back at the Liceu, opposite the Spanish diva Montserrat Caballé, in Donizetti's "Lucrezia Borgia." Conquests in London, Paris and New York quickly followed.

His first recording for a major label, the youthful Verdi's Donizettian comedy "Un Giorno di Regno" under Lamberto Gardelli (Philips), documents his winning grace, a timbre darkish for a tenor yet lyric and fresh, a manner both elegant and bold. He went on to record some three dozen operas, with Mr. Gardelli, Colin Davis, Riccardo Muti, Claudio Abbado, Alain Lombard, Lorin Maazel, and Herbert von Karajan, of whom Mr. Carreras became a special favorite. Karajan was notorious for tempting lyric voices into strenuous dramatic parts, with disastrous consequences, but Mr. Carreras needed no tempter. Most of the roles Karajan offered him -- Don Carlo, Radamés, Cavaradossi, Don José -- he had sung before, frequently.

In his autobiography, "Singing From the Soul" (Y.C.P. Publications), Mr. Carreras writes of the kinship he feels with Calaf in "Turandot" the unknown prince who risks his life to win a man-killing princess, "especially when he sings the finale, 'Vincero!' 'I will win! I will win! I will win!' " Calaf's romanza was the last encore of Mr. Carreras's come-back concert in Barcelona on July 21, 1988 - and also of the famous Three Tenors blockbuster at the Baths of Caracalla in Rome on July 7, 1990 (a runaway best-seller on London CD and video).

"I could have had a comfortable life singing just two or three roles," Mr. Carreras said.,"But you have to learn the borders of your possibilities. Basically, I have a lyric tenor voice. Maybe the color is dark, and maybe this allows me, with the right musical and dramatic accents, to sing heavier dramatic roles. I don't mind losing a certain purity if I can be more intense. At the end of the day, what counts is the expression, not just a beautiful sound. Some of my greatest successes have come in roles some people thought I shouldn't have sung. First let an artist show what he can do."

When sickness struck, Mr. Carreras was in Paris, at work on a movie of "La Bohème." He checked into the American Hospital, and on Bastille Day 1987 his doctors ordered a spinal tap. Two days later, they announced the diagnosis of leukemia. Then came the bone-marrow transplant in Seattle, the 150,000 get-well letters and the long, hard recovery.

Mr. Carreras has since founded the José Carreras International Leukemia Foundation, performing in benefits with the elite of the opera world and raising funds for treatment and research -- more than $10 million to date. When his singing days are over, he expects to devote himself to the foundation's work full time.

But right now, Mr. Carreras is sounding like a busy singer, not a figurehead. For the time being he plans to sing some 50 performances a year. Coming soon are varied opera and concert engagements at La Scala, Covent Garden, the Zurich Opera House and the Salzburg Festival. With Mr. Pavarotti's encouragement, Mr. Carreras is contemplating taking up Donizetti's Nemorino again, in "L'Elisir d'Amore," purest bel canto, the sort of thing many early admirers wish he had never left behind. "It's wonderful," he said, ''for the health of the voice."

Mr. Carreras may be leaving the past behind, but the world is not likely to. Is he conscious that he has become a symbol, in some sense sanctified by his ordeal? "If the fact that I overcame such a terrible disease, and that I'm an artist and a singer who is more or less known -- if this gives people who are suffering the same thing now the courage to believe that it can be beaten, then I'm very happy."

Matthew Gurewitsch has written about the arts for The Atlantic Monthly and Mirabella.

Copyright © 1992 The New York Times