Any attempt to set out an appreciation of Maria Callas in words is a failure before it begins. She and her art were inseparable, and that art was a magnetic, incomparable combination of the art of singing and the art of acting. For so singular an artistic phenomenon as Callas, it seems best to let those who knew her and worked with her most closely do the speaking. And we should read what Callas wrote about herself.

Callas attracted some of the world's greatest conductors. Among them were Tullio Serafin, her first and greatest mentor; Erich Kleiber, Herbert von Karajan, Leonard Bernstein, Carlo Maria Giulini, Dimitri Mitropoulos, Eugene Ormandy, Victor de Sabata, John Barbirolli and Thomas Schippers. One of the conductors with whom she often sang, but who is less well known in this country, was Antonio Votto, who frequently conducted Callas in "La Gioconda" at La Scala. Votto called Callas "the last great artist." His description of the way she worked in spite of her severe lifelong myopia is only a part of his remarkable tribute:

" . . .This woman was nearly blind, and often sang stading a good 150 feet from the podium. But her sensitivity! Even if she could not see, she sensed the music and always came in with my downbeat. When we reheasal, she was so precise, already note-perfect. Even in rehearsal she always sang full voice." This was a habit she shared with Kirsten Flagstad. Votto continued, "Most singers are stupid and try to save themselves, but a rehearsal is a kind of hurdle. If in track you must run a mile, you don't practice by running half a mile. For 30 years I was Arturo Toscanini's assistant, and from the very first rehearsal he demanded every nuance from the orchestra, just as if it were a full performance. And Callas did this, too. She was not just a singer, but a complete artist. There is no one like her today. She was an esthetic phenomenon."

The Callas career saw her singing 535 perfomances in 43 operatic roles, plus around 100 concerts. The roles she sang the most often were, in numerical order: Norma (84), Traviata (58), Tosca (53), Lucia [WORD ILLEGIBLE] Lammermoor (43) and, in a tie at 31 each, Medea and Aida. To these she added such other famous parts as Isolde, the Walkuere Brunnhilde, Kundry, Elvira in "I Puritani," Lady Macbeth, Gioconda, Mozart's Constanze, Haydn's Euridice, Rossini's Armida, the Leonaras in "Forza," and "II Trovatore," Butterfly, Fedora, Rosina, Gilda, Amina and many others. And she recorded four roles that she never sang never sang on any stage: Nedda in "Pagliacci," Mimi in "Boheme," Manon Lescaut in that opera and her famous and controversial Carmen.

Jussi Bjoerling, whom many considered the finest Manrico to be heard in "II Trovatore" since Caruso, sang that part opposite Callas only twice. He said of her, " She was the greatest Leonora I ever heard."

Another tenor great, Jon Vickers, who joined Callas in some historic performances of "Medea" at La Scala, said, "There are some who thing they are following in her shoes, but believe me, they don't know which direction she was going. I not only learned a great deal about the stage from her, I learned how the public image of an artist can be unjustly distorted. She was a superb colleague, giving you something to work with and wanting you to give it back. She never tried to steal the limelight or upstage anyone."

In the opinion of Carlo Maria Giulini, who conducted some of the greatest Callas Traviatas, "She was one of the few performers I have known - for whom the last performance was as important, as fresh, as exciting as the first. Maria had a dedication to her work and to the theater, and she had the desire to give to the public."

With her intense working habits, Callas attracted not only the finest conductors, but also a remarkable series of notable stage directors, each of whom found astonishing elements in an artist whose name had become so widely used. Franco Zeffirelli said simply enough, "Maria never erred artistically."

Margharita Wallman was preparing a production of Gluck's "Alceste," with Callas in the title role. She had told Callas that she would not need her one day before noon, because she would be working with the chorus. But, Wallmann later recounted, "When I arrived at 10, to my surprise, there sat Maria. 'But dear,' I said, 'you don't have to come for another two hours.' She replied, 'I want to watch you work with the chorus. That way I will get in the right mood and know what I must do.' What other major artist can you name," asks Wallmann, "who would sit for two hours in an empty auditorium observing a chorus rehearse just to understand the overall quality of a production?"

Luchino Visconti, who was responsible for helping to make the Callas Violetta something unforgettable, said, "I can only say that Maria is possibly the most disciplined and professional material I have ever had the occasion to handle."

George London, who sang Scarpia opposite the Callas Tosca at the Metropolitan Opera under the Mitropoulos baton, has spoken of her gift of acting without movement, of commanding a stage while immobile, a gift London share with the great soprano. London summed up much of the Callas secret when he called her gift "an inner spiritual and artistic motor, something which is always running and is part of an internal identification with character. That kind of energy, which is an energy of the mind and spirit, has an irresistible thrust into an audience. But to work, it requires an innate dramatic personality. you can't teach it to someone. You can't create a Callas out of Miss X, even if she were to do in every detail what Callas did in a given situation onstage, because it came from Callas' inner strength and that cannot be fabricated."

At every moment of her career, Callas knew precisely what she was doing and how she was doing it, for all that some of the highest moments seemed improvised. Their spontaneity was the final product of long, searching study. When she began to have severe vocal problems, she knew that, too. She said, "My biggest mistake was trying to intellectualize my voice. It set me back years. Everyone thought I was finished. I tried to control an animal instinct instead of leaving it as it was - a God-given gift."

But the impact Callas made during her great years is one that left no one who was exposed to it quite the same afterward. Some hated it. Some adored it. Beverly Sills said, "I would rather have 10 sensational years like Calllas than 20 years like another."