NEW YORK -- Katharine Hepburn was fascinated with Spencer Tracy but says in a rare interview that she had little idea of how he felt about her.

Speaking about their 27-year friendship, the actress said she conducted her relationship with Tracy with great restraint.

"I never went out in public with Spencer," Hepburn told Newsweek magazine. "I never, ever did. Ever. Mrs. Tracy lived in California and he was married to Mrs. Tracy and I didn't think it was my place to be seen all over town with him."

Hepburn, 77, who dismissed the idea of an autobiography as "boring," has, however, written "The Making of 'The African Queen': Or How I Went to Africa With Bogart, Bacall and Huston and Almost Lost My Mind." Excerpts from the book accompany the cover story about Hepburn in Newsweek's Aug. 31 issue.

Hepburn is philosophical about her ties with Tracy and about relationships in general.

"I don't think you can analyze why in the hell it is that you can get on with one person and you can't with another," she said. "You could see that he fascinated me. I have no idea really how he felt about me."

Friends in Hollywood kept quiet about their relationship. "They respected it for the reason that I respected it and Spencer respected it. We went out of our way to be reticent. And I think people thought, 'Well, if it means that much to them, let's shut up.' "

Marriage was out of the question, she said.

"I'm not a great believer in marriage, anyway, unless you get married for a reason, and that is to have children," she said. "He had two children, and we certainly didn't want {any}."

Growing old doesn't bother her, she said.

"People should try to keep themselves as mobile as they can, but not with the terror of fighting a monster," she said. "Because then you have to say, 'Would you like to go on living forever?' I say, 'No, please.' I'm not afraid to die. I think I'll just go to sleep.