The doors of the recital hall swing open, seemingly of their own volition-mythically-and in sweeps the diva, taking the stage with nothing less than divine right. "No applause," La Divina warns us, throwing up a halting hand. "We're here to work."

And work she does! When "Master Class" lets out at the Golden Theatre more than two hours later, one legend has been unraveled and illuminated by another, and the applause is positively deafening.

Zoe Caldwell is not tall, she is not Greek and she is not even a singer, yet during this buoyant crash course in how life and love inform one's art, she manages to convince you she is all three—that she is, in fact, Maria Callas, the soprano whose decade of artistic ascent at La Scala in Milan more or less defines, for all time, divadom at its most advanced state.

"But that," as the character never tires of saying, "is another story." The Callas encountered in "Master Class" is a diva whose risk taking has caught up with her. The glorious voice has long since deserted her, and she is left-humanized, if not notably humbled-with the life lessons she picked up during her amazing, meteoric career; it was these as much as her musical counseling that she imparted in a series of by-audition-only tutorials she conducted at Juilliard in 1971 and 1972-truly, a voice of experience addressing the untested generation behind her.

"This is her during the master classes," La Caldwell says, singling out a specific shot among the Callas collage plastered across a section of her dressing-room mirror. "She auditioned 350 students, took on a dozen and did a series of master classes with them in one of the big rooms upstairs-and they were packed!" In that original number was the author of "Master Class," Terrence McNally, who transposed the event into a complex and compelling exploration of the creative spirit. The Caldwell Callas that resulted, like "The Lisbon Traviata," is a stylistic extension of McNally's operatic obsession.

"It is not a docudrama," cautions Caldwell, who studied audio tapes of the actual classes. "It is a play, and being a playwright, he evokes his own Callas. When he sent me his first draft, it was a one-person show, and that didn't interest me. Then he did some more work on it and brought out the interdependence of the students she's critiquing. That did interest me."

Three gifted young singers—two sopranos (Karen Kay Cody and Audra McDonald) and a tenor (Jay Hunter Morris)—are flung on the diva's pyre, along with an obsequious accompanist (David Loud) and an apathetic stagehand (Michael Friel). The interplay, under the direction of Leonard Foglia, adds layers and dimensions to La Divina. She brays, she flays, she browbeats, she weeps, she hallucinates—and all of the above in high heels. "I'm dressed by Chanel, as was she, and they said, 'You must wear our shoes,' so I am. For the whole show I'm constantly on my toes."

Not that the Melbourne-born actress, classically trained in England's West End and Stratford-on-Avon, could ever be otherwise. In the dazzling swing of emotional notes she hits as Callas, she runs a career-crowning gamut—no small achievement for one who has already played the best stages in the world opposite the likes of Laughton, Olivier, Gielgud, et al. "This is a very demanding role—this is a Lear—because, from the moment I walk onstage, it is up to me to keep everything churning along. Vocally, it's very fatiguing because I play on so many different levels."

But, giving credit where credit is due, it is a part for which she is superbly and intrinsically suited. When she is not professionally engaged as a performer, Caldwell occupies herself much as Callas does in "Master Class": teaching ("I have what is laughingly called the Visiting Eminent Scholar Chair" at Florida Atlantic University in Boca Raton) and directing (plays with two strong characters at the core are her specialty: James Earl Jones and Christopher Plummer in "Othello," Plummer and Glenda Jackson in "Macbeth," Jason Robards and Judith Ivey in "Park Your Car in Harvard Yard," Vanessa Redgrave and Eileen Atkins in "Vita & Virginia").

"Medea" is yet another common denominator for the two divas, and Caldwell believes Callas played the part offstage as well-particularly in relation to her high-profile affair with Aristotle Onassis, the shipping tycoon who always said his favorite part of opera was the interval. "The thing that stunned me the most about Callas in my research—two things, really—was what a supreme musician she was and how she gave it away in the name of love. She gave Onassis her magic—just as Medea did to Jason—and he threw it away. In a very real way, Callas herself was a Greek tragedy."

Fortunately, domesticity has spared Caldwell the lower depths of divadom. In 1966-the year she turned in her first Tony-winning performance (in Tennessee Williams's "Slapstick Tragedy")—she met and married producer/director Robert Whitehead. They have two sons (Sam, 26, and Charles, 23) and a famously effective professional relationship: Whitehead produced her second Tony-winning vehicle ("The Prime of Miss Jean Brodie"), directed her third ("Medea") and is now bankrolling what could well be her fourth.

But that Tony, if it comes, is not the light at the end of the tunnel for Caldwell. "What I'm really looking forward to, after 'Master Class' has run its course, is a nice, long cruise with my husband. We travel a lot. I don't want to just be always working. I also have a very good life with Robert, and that's very important to me."

Finally! A diva who allows herself a happy ending!

-- By Harry Haun