Uniquely favored by nature and circumstance, Suzanne Farrell, at 40, already holds a secure place among the immortals of ballet. She's the most extraordinary ballerina this country has produced, and if you've witnessed her radiance in "Diamonds," her fiery grandeur in "Walpurgisnacht Ballet," her swooning delirium in "Vienna Waltzes," her amorously poetic "Symphony in C," her tempestuous "Tzigane," the profundity of her "Mozartiana," or dozens of other peerless interpretations one could name, you don't need to ask why. If you haven't, you've missed one of the sublime theatrical experiences of an era.

Of all the heirs to George Balanchine's creative legacy, Farrell is the richest, not by virtue of possession, but because he made more ballets for her than any other dancer -- 23 in all, most of them masterpieces. And Farrell still sees Balanchine as a presence in her life: "I don't feel I'm conjuring up ghosts," she says, "but it would be the most normal thing if I just ran into him on Columbus Avenue, as I used to so many times."

Balanchine, Lincoln Kirstein relates, would occasionally refer to Farrell as "my Stradivarius." But the flesh and blood Farrell is a more exceptional performing "instrument" than any object of wood and gut, no matter how euphonious or highly prized. Kirstein has also told us more than once that to the deeply religious Balanchine, dancers were "angels, messengers of movement who are sent . . ." If such a conception strikes you as arch or antiquated, Farrell is the one to convince you otherwise.

For the New York City Ballet's opening night program last Wednesday, Farrell appeared as Terpsichore in Balanchine's "Apollo," a performance she'll repeat tonight at the Kennedy Center Opera House. It's the last she'll be seen here this year. Farrell also portrayed the tragic heroine in the Washington premiere of Jerome Robbins' "In Memory of . . .," set to Alban Berg's Violin Concerto, this past Wednesday. She recently talked about the role, as well as other aspects of her life and art.

The Berg score was written as a memorial to a young girl, Manon Gropius, of whom he was deeply fond and who died of polio at 18. "I didn't know the music at all," Farrell says, "nor had I danced ever to any music by Berg. The only association I had was that Mr. Balanchine once talked of doing a 'Salome' ballet to Berg's 'Lulu' score. He mentioned something about there being a tower in it, and that's as far as we got.

"Actually, though, I prefer to come to a score fresh, like this, because I feel otherwise I might be painting the choreographer into a corner. Music inspires me to move. If I know the music too well beforehand, I might tend to move in a certain way, and the choreographer would then have to tear down that barrier."

"In Memory of . . ." is basically an "abstract" ballet, though its general dramatic outline -- of a young women who meets an early death and undergoes a kind of transfiguration -- is clear. Farrell, so often linked to abstraction because of her affinity for Balanchine's plotless works, nevertheless relishes the dramatic implications of a work like the new Robbins.

"I must say I've always enjoyed having a character to portray. People have this idea about so-called abstract ballets that it's leotard and tights and that's it. They don't realize that just because you don't have a peasant costume and a daisy it doesn't mean the dancing can't involve emotion or feeling. You don't have to emote all over the place -- you can have emotion without being 'emotional.' Even in dancing a storyless ballet like 'Symphony in C,' I feel there's a story in a musical-emotional sense -- you build to a climax, and that's drama. I feel this way even when I'm doing the same ballet with a different partner. I'm looking into a different pair of eyes, I'm being held in a different pair of arms, the nerves are different, and the chemistry, and so there's a different emotion."

As for the "hidden" reference to Balanchine in "In Memory of . . ." that so many critics have detected (Balanchine died two years ago, and this was the first ballet Robbins had done in some time with Balanchine's most treasured dancer), Farrell says, like Robbins, that it wasn't a conscious intention for her. "I think about Mr. B. all the time, so it wasn't anything out of the ordinary in that way for me, I wasn't really connecting the role with him."

Farrell says that the special nature of her relationship with Balanchine hasn't prevented her from enjoying working with Robbins, or other choreographers for that matter, including Maurice Bejart (whose company she joined for a five-year period in 1970), and her husband Paul Mejia, resident choreographer of the Chicago City Ballet.

"I give myself as fully to them as I did to Mr. B.," she says. "When I was working with Jerry Robbins on 'In Memory of . . .,' my belief in him was complete. You either believe or not -- you can't semibelieve. Balanchine always gave himself completely to every ballet he worked on, always one-hundred percent. If you're given something and you keep it, it's gone when you are. If you give something away, it's forever."

There are, of course, differences in Farrell's experience of working with various choreographers. "I think some choreographers feel, in making a ballet, like they're having a baby. They realize they have to be willing to give it away, but they feel when you are choreographing, you're in control; once the dancer takes it, you have to let it go, and you've lost your baby."

On working with Robbins, she says: "Jerry always knows what he wants the choreography to look like, but he's not always sure of what steps will get him there. He'll tend to make several versions, A, B, C, D, of the same ballet, and you won't know which he'll end up sticking with -- it's another reason it's good not to know too much beforehand about the story or music, so you as a dancer don't get too committed prematurely to any one version. Jerry talks a lot more in working than Mr. Balanchine did, and you have to listen all the time, even though it ends up only half of what he said is what he really wants you to remember. Mr. B. didn't say much, and you listened because you were afraid he might not say it again. Both methods are fine with me."

The facts of Farrell's life bear simple telling. Born in Cincinnati, she started dancing at 8, auditioned for Balanchine on her 15th birthday, was given a scholarship to the School of American Ballet, and joined the New York City Ballet in 1961. In 1969, she married fellow dancer Mejia; the couple left the NYCB and spent a number of years abroad -- a painful break at the time. Farrell rejoined Balanchine in 1975, and worked with him on all of his later major ballets.

She's managed to put his loss behind her, in the true Balanchinian spirit of living for "now."

"In the beginning it was hard for me to hear his voice on a tape, for instance -- it was too painful. But now when I look up and suddenly see him, it's so natural . . . He just seems to me to be always with us now. Of course, he told me he was a Georgian and that he'd live to be a hundred and I believed him. But when I see him now, I don't see those last days in Roosevelt Hospital. Chronologically, those were my last memories -- but they are not my last memories."

When she was working with Balanchine, Farrell addressed him as "Mr. Balanchine," or "Mr. B." "He was always 'Mr. B.' at work. As close as we were, when we were in class he was still my boss -- that's the way it should have been, and that's the way I wanted it. He'd ask me to call him George, and I sometimes did, outside. But I never felt comfortable about calling him George in front of other people. He'd call me 'Suzy.' No one did that in the ballet world. I'd been Suzy to my mother and sisters. It was strange to hear him call me 'Suzy.' "

Their relationship was never very verbal. "We didn't sit down and discuss. We just sort of understood. That's why it worked so well. I can't really analyze it beyond that. Mr. B. and I, we were always very fast -- I mean, we were quick. When you'd ask him what he was thinking about, and he'd say, oh, a million things, he really was.

"I'm like that; I can do a lot of things all at once and still do them all completely. People say to me, oh, you're so fast, you pick up steps so easily, you must have a photographic memory. Maybe there's a certain facility, but the fact is, I trained my mind to absorb steps rapidly and associate them with music. I had to, when I realized the value it would have, and it's not just in dance, it carries over into other things."

Many things have gone into the making of Farrell's artistry, not the least of which is that dancing and its ceaseless regime of practice is a form of labor she loves. "I like the 'work' that's involved in dancing -- the hours in the studio, the classes, the rehearsals, the repetition. Yes, the real thrill is to go out and perform, to make people happy, to have the excitement of the theater. But I'm not intimidated by having to struggle. I can be embarrassed. I don't always have to look great. Nothing is born with all its plumage -- you grow into your feathers. A rose can be pretty at different stages of its development. When I first started with Mr. B., I was just struggling like everyone else, trying to do the things he asked us to do. I never wanted to be a 'ballerina.' I only wanted to dance."

On stage, dancing, Farrell exudes a wonderful aura of spontaneity and confidence. Yet in a recent interview elsewhere she said, "I'm probably more insecure than most people." Expanding on this theme, she says, "I'm secure in knowing that I'm going to do something, but I'm not sure how. I'm not unprepared -- I know the steps, I know I can count on my professionalism to get me through. But I haven't calculated exactly what I'm about to do outside the basic structure. What's the point in doing it again, if I had? You may as well run a tape.

"In the same way, people always ask me do I have a favorite role. No. It's the one I'm doing at the time. It would be terrible to dance one role and be thinking of another. What I do is listen to the music, and dance to the music. Every note you hear, whether you're dancing that moment or not, is building toward what you hope to achieve in your dancing. Every note is a stepping stone. I can't start a ballet thinking of the level I'm going to reach -- that would rob that moment of its quality. So I'm never sure what's going to happen once I get out there. Because I haven't heard the music yet -- as it's going to be played then."

Is there life outside the dance for Farrell? "Not much," she says. "Naturally you sacrifice a lot for this kind of life. But you win in the end, so you're not as brave as you thought you were. You give up something to get something. What's wrong with liking your work?

"I'd like someday to do a good Broadway show. When I'd tell this to Mr. B., he'd say, 'Oh, you don't need that now.' When I came back to the company, the ballet had to come before anything. But I like the Broadway kind of music, too -- I've had a little of it in 'Slaughter on Tenth Avenue' and some of our lighter ballets, and Paul Mejia did a ballet for me to jazzy music. I also enjoyed it when I did some acting and dancing on TV -- the scope was so different. I had to underdo, yet without losing it. I did a segment of Tony Randall's "Love, Sidney" show, in which I played a ballet teacher. It was filmed live in front of an audience. Mr. B. had just gone into the hospital, and it gave me the distraction I needed then."

Farrell's two-city marriage is another fact of life she's adjusted to. "Well, it's inconvenient at times. But a dancer's life is such a short one, and I want to be dancing as often as I can. When I am, I don't see Paul anyway. So, with the commuting, we see each other almost as much as if we lived in the same city.

"The phone bills are something, it's true. When we were first married we had five years of being always together, and that was nice. But now I enjoy the opportunity to work with the Chicago City Ballet and to work with Paul as a choreographer. I have to say also, prejudice aside, that I think he's very talented."

Inevitably, Farrell has given thought to what her life would be like if she should stop dancing, and almost predictably has come to no conclusion -- that wouldn't be living now. "Naturally I've thought of what I would do, but I don't know how I'll feel at that time. Will I choose to stop dancing, or will I be forced to? I don't know. It's difficult to be a conscientious performer and an observer of oneself at the same time. At the moment I'm performing, I don't see what it's looking like. I know what it's looking like, but I don't see it -- I'm not looking at, I'm looking out. When I'm dancing in 'Apollo,' it's Apollo and two Muses for me; I don't see a third person with my eyes.

"I can always teach -- I've been teaching since Mr. Balanchine started me on it at 19. Unless I choose to do something completely different. I enjoy teaching because I'm still performing. There's nothing so wonderful as performing. I can't imagine anything being as wonderful as what I've been doing."