He was a "preemie" weighing less than three pounds at birth, and his father, an uneducated Bahamian tomato farmer, prepared a casket. Fifteen years later Sidney Poitier left Nassau for Miami and, through a combination of naivete and will, went on to become Hollywood's first black leading man. His movie breakthrough was Cry, the Beloved Country in 1952. Then came The Blackboard Jungle (1955), The Defiant Ones (1958), A Raisin in the Sun (1961) and Lilies of the Field (1963), which won him a Best Actor Oscar—the only one ever for a black (Hattie MacDaniel was Best Supporting Actress for Gone with the Wind). Poitier's monopolization of the few roles then available (including Heat of the Night in 1967) led to resentment by other black actors.

Poitier's first marriage, to model Juanita Hardy, produced four daughters (now 28 to 19) and ended during his nine-year affair with actress Diahann Carroll. In 1976 he wed Canadian-born actress Joanna Shimkus, who had played opposite him in The Lost Man in 1969. They and their two daughters, 8 and 6, live in Beverly Hills. A charter member of the now defunct First Artists Co. with Streisand, Newman and McQueen, Poitier turned to producing and directing with Uptown Saturday Night in 1974. Then, abruptly, in 1977 the Bahamian émigré who had had only a year and a half of formal education took two years off to prepare a memoir. Typically of Poitier, he did not use a ghost, and the now published result, This Life (Knopf, $12.95), is a powerful work. In the meantime he returned to direct Stir Crazy, Richard Pryor's last work before his near-fatal accident in June. With Lois Armstrong of PEOPLE, Poitier discussed his extraordinary 53 years.

Why did a "terribly private person," as you describe yourself, write such a revealing autobiography?

My years had been so full I wanted to itemize them while I was still lucid. More important was that people, including even those close to me, tend to relate to the image of me projected in my films. I felt it absolutely imperative that my children be dissuaded from that myth. I wanted to leave them a truer accounting.

What was your state of mind when you came to the States?

I was imbued with my idyllic life in the Caribbean, where there was sunshine and turtles and birds and no white people. It never occurred to me that I couldn't come to America and do whatever I wanted to do. Naive as that was, it was a blessing.

Still, didn't you start out washing dishes after moving from Miami to Manhattan?

Yeah, and I was sleeping on the roof of the Brill Building and using the New York Times for a blanket. I had nothing but summer clothes that first winter, and I froze. I got arrested for vagrancy for sleeping in Penn Station one night, so just to have something to eat and a place to sleep, I joined the Army. I fudged my age by two years to get in.

Why did you become an actor?

After the Army I picked up the want ads one day, and I saw dishwashers and porters wanted on one page and actors on the other. I had done those other jobs so I thought maybe I should go see what this acting was all about.

What happened?

It was the American Negro Theatre, and before I had read three lines the director threw me out. He said, "You can hardly read and can't be an actor with an accent like that." That made me determined. I got another dishwasher's job and bought a $13 radio and repeated back everything I heard on it until I got rid of my Bahamian singsong. Meanwhile an old Jewish waiter at the restaurant where I worked helped me with my reading every night. After six months I went back and was accepted.

You met Harry Belafonte at that theater. Do you still see him?

Our relationship is as it always was—resilient, enriching and, on occasion, frustrating. I think I've shared more with him than I have with any other man I know. If Harry B's there for you, he's there all the way. But he can be the worst SOB that God ever created. You've got to be terribly special to him to be excluded from his guillotine when he's out for blood.

When did your affair with Diahann Carroll begin?

We had not been on the set of Porgy and Bess in 1959 more than a few days when I realized that she was unique. She had fantastic cheekbones, perfect teeth and dark, mysterious eyes. She was confident, inviting, sensuous—and she moved with a rhythm that absolutely tantalized me. I invited her to dinner, telling her that since we were both married we would talk about our absent loved ones. And we did. I acted very, very gentlemanly for weeks, but halfway through the picture we fell in love. As I got to know her, I realized she was one of the brightest women I had ever known.

Although you told your wife about Diahann right away, why did it take you six years to end the marriage?

To a large degree I felt trapped by my four daughters. They were young and I loved them. And my father had thoroughly indoctrinated me when I was young that, as a law of life, a parent should take care of his children even if it means not putting food in his own mouth.

Did your daughters resent you?

I think there was a time when they were as mad as hell at me because of the threat to their own security. Although I never severed links with them, I was a villain of sorts in their eyes. The relationship is now very healthy and free-flowing, but getting it there tested our strength and perseverance.

Why did you and Diahann finally break up?

She asked me to move out of my home, and I did. She asked me to get a divorce. I went to Mexico and got one. I made one request: to live together for six months while Diahann's parents looked after her daughter so I wouldn't be jumping from one marriage straight into another. But she wouldn't do it. It was then that our relationship started to unravel.

In Guess Who's Coming to Dinner, how was it to work with Spencer Tracy and Katharine Hepburn?

Terrifying. I was so awestruck I forgot all my lines. Finally I asked Stanley Kramer, the director, to let me play my lines to their empty chairs.

What did you think of black exploitation movies like Shaft and Super Fly?

Like everyone else, I put down my $3 to watch Jim Brown and Fred Williamson do their stuff—see the black guys beating up on the white guys for a change. It was delicious. I also enjoyed watching my fellow black actors getting work.

Did your own career suffer at that point?

Sure, a shift in the tide had taken place, so I bought a boat and a lot of books and just went down to the Caribbean and cooled it for about a year. I didn't particularly relish criticism of my work then as "too white"; in fact, I hated it. I got a lot of bad vibes from some of my actor friends, too, but Jim Brown did something that really touched me. We happened to be on a plane together one day, and he came over and thanked me for the contributions I had made "to give us all a little piece of the action."

What finally soured you on the black macho films?

After a few years I saw that the producers were only in it for the buck and weren't interested in the hopes and aspirations of black people.

How did you feel about your comeback directing Uptown Saturday Night?

It confirmed that black people were weary of seeing themselves as pimps and prostitutes and that white America would go to see a black film if it's about an aspect of life that interests them. It also underscored the fact that blacks are going to have to keep making our own films, not rely on whites to champion our dreams. It's very difficult, but not impossible. The coming age of video discs and satellite cable systems, I think, will present a vast opportunity to black filmmakers to create for their culture.

Would you ever act again?

Only if a piece of material comes along that compliments my years.

Do you feel satisfied now?

I have lived such a tumultuous life, so many lifetimes in 53 years—it's been an incredible journey. But I want to spend more time with my wife, Joanna, and my family and more time doing simple things like writing, reading, walking on the beach, thinking about the earth and the stars and listening to other drums. I want to be at peace internally and continue to feel good most of the time. But, yes, you are looking at a man who is relieved. I have nothing more to prove.