Certainly, no figure in the musical theatre is more visible than Stephen Sondheim. The theatregoing public recognizes his rumpled, bearded, half-smiling image instantly. We think we know him well. After all, he's been in the public eyes for four decades.

Meryle Secrest's new biography, "Stephen Sondheim: A Life" (Knopf) (scheduled for publication June 14) may reveal just how little we do know about him. A musical maven may be able to pull up any number of facts and stories behind the creation of Sondheim's many revered works, from West Side Story to A Little Night Music to Sunday in the Park With George. But how much does anyone know about his singular childhood, one that saw the young prodigy in this hands of servants during his formative years, abandoned by his father at age 10, in military school a year later, and at the mercy of a willful, selfish, possessive and often drunk mother during his teens?

The book paints an intriguing picture of a personality with innumerable and sometimes opposing sides. Sondheim is forbidding yet friendly; analytical yet romantic; distant and cold, yet generous and protective toward his friends. He is a sensitive, often morose aesthetic, whose idea of a good meal is a large steak washed down with scotch. He's continually viewed himself as an outsider, an outcast, yet, as the protege of Oscar Hammerstein, ran in Broadway's inner circles from his earliest days.

Secrest captures all these contradictions while not pretending to resolve them. The biographer (whose next subject, ironically, is onetime Sondheim collaborator Richard Rodgers) paused during her current book tour to talk to Playbill On-Line.

Playbill On-Line: Sondheim has a reputation for being a very private man. How did you convince him to cooperate for a biography? Meryle Secrest: I know I'm going to be asked this a lot. I really didn't have to do that much convincing. It's entirely possible I came along at the right time. We all have certain moments in our lives when things happen. I think Sondheim is in a fairly elegiac frame of mind these days. It did take a while. I brought up the subject when I was working on a Leonard Bernstein biography. He wrote back saying `Thanks, but no thanks.' A year later, I brought it up again -- we'd been in friendly touch. I said, `You're sure you haven't changed your mind?' He said no. Something happened in the next three months to change his mind. He had read the book of Bernstein, his friends had read the book, and liked it.

PBOL: Were there certain subjects which were still off-limits?

MS: No. We'd talk about whatever he wanted to talk about and whatever he didn't want to talk about was fine with me. He just followed his nose. There weren't any topics that I asked about that he didn't bring up. There were times when I was in my 20s and 30 that I thought a public figure had a duty to tell the world anything people wanted to know about him. I don't feel that way now. I think that was the approach he liked. He's such a private person. I would have made a great psychological error if I had approached it any other way.

PBOL: He has rarely, if ever, discussed his sexuality. Was this a particularly difficult topic for him to talk about?

MS: I think it was. Don't forget, there has been a huge shift in attitude toward homosexuality. Not so long ago, people could be blackmailed. Nobody would volunteer that he was gay. Now everybody is more comfortable about that. Back then they weren't. When I came to America in 1953, and married my husband, who was American, I was amazed by the bigotry of the things my husband and his friends would say. Calling someone queer was about the worst thing you could say about anybody. To me, [Sondheim's reluctance] is perfectly understandable. It's just good common sense. Also, maybe he thought it was nobody's business.

PBOL: What do you consider the book's most remarkable revelation about the man?

MS: I don't know. You're too close to a subject to see it for yourself. What I was trying to do is draw a portrait of a personality. I had the wrong idea about him. I thought he was introspective and eccentric. Now that I know him much better, I see I was quite wrong. I hope I can alter the misconceptions about him. There was a story in the New York Observer when his house was burned. It said Sondheim was reclusive, eccentric. This isn't true. He's an immensely gregarious person. He's always surrounded by people; he hates to be alone. He is intensely funny. His moods are mercurial. I'm sure he wouldn't agree, but this is how I see him. He will be in despair today, and the next day he's fine. I don't think he sees how wild his mood swings are. This is a complicated man we're dealing with. I think it comes through in the music. You have to be in touch with your feelings to write the music he does.

PBOL: To what extent do you think Sondheim's relationship with his mother formed his character?

MS: You could say to what extent my relationship to my mother formed my character. Of course, everybody is profoundly affected by his or her mother. I think a lot of Steve's wariness where others are concerned had to do with her. He had a terribly difficult mother. Lots of us had difficult mothers. I think he's very wary of closeness and it's something that he is aware about himself. But you can't discount the impact of his father. This is a man who left when he was 10, in the middle of the night, without a word. He just left a note of his wife's pillow. [Sondheim] was just entering manhood and the father was gone. The absent father had as much to do with who he is as does his mother.

PBOL: Of all the shows you discussed, which do you believe had the most fascinating story behind it?

MS: I think Passion, really. In a way, it's a work that has a lot of things wrong with it, but to me it came at the pivotal moment in his life. He deals with the idea that he's madly in love. He was attracted to Passion for that reason, and the way love is described in it is the way he sees love. Peter [Jones, his partner,] enters his life at that time. Steve's experiencing a lot of feelings. For that reason, it's an interesting show. Of course, my favorite of his shows is Sunday in the Park with George, because I come from an art background.

PBOL: Many artists experience a fallout of creative energy and inspiration in their later years. Do you think Sondheim is experiencing that?

MS: I don't think so, no. He just goes through the normal creative process of writing wonderfully and then having a huge lack of confidence in what he just wrote. We on the outside just don't know how impossible it is to put together a good musical. I wonder how anyone ever does it.

PBOL: What are the challenges of writing a biography of someone who is yet living?

MS: There are many. Steve and I discussed it. I think, coming from journalism, I tended to think there was one right way to describe someone. There is not one definitive way. You bring to the subject your own point of view, your own prejudices. My view of Sondheim can not possibly be his view of himself. I warned Steve he would not recognize himself. And, I must say, he was an absolute brick about himself. He's a collaborator. He puts together things with many other disparate talents. So, he expects things to look differently than the way he envisioned them.

PBOL: Did he see the manuscript before it was published?

MS: He and I agreed he would see it for factual errors. I had grave reservations about it. I'd never agreed to something like that before. But he was as good as his word. He did not touch a word about my perceptions or thoughts about him.