James Stewart was talking the other day about one of his favorite co-stars, a 6-foot pooka named Harvey.

What's a pooka? It's an oversized rabbit, considered fictional by most folks, but very much real to Elwood P. Dowd in the 1950 movie "Harvey." The Universal Pictures comedy has been released for home video, along with a six-minute introduction by Stewart himself."Coming back in video - I kind of like the idea," he remarked in an interview at the Beverly Hills Hotel. "People can see the whole picture with no interruptions for anything.

"It seems that in the mail I've gotten for the past 10 years, almost everybody speaks of `Harvey.' It's one of their favorite pictures."

With Henry Koster as director, the movie is all about Elwood, who is in his early 1940s and shares a house with his older sister, Veta, and niece, Myrtle Mae. He is the most considerate of men, forever holding doors open and offering invitations for dinner, a penchant for martinis his only vice.

Why is he so happy? According to Elwood, he was walking down the street one evening when he encountered a large, white rabbit leaning against a lamppost and the two became instant soulmates. Elwood has no job - a large inheritance took care of that - and no sweetheart, but always has a wonderful time thanks to the towering and invisible presence of his dear friend, Harvey.

"Harvey and I have things to do," Elwood says. "We sit in the bars...have a drink or two...play the juke box. Very soon the faces of the other people turn towards me and they smile. They say: 'We don't know your name, mister, but you're all right. All right.' Harvey and I warm ourselves in these golden moments."

Stewart traced his history with "Harvey," Mary Chase's Pulitzer Prize-winning play with the gentle message of who's sane and who's not.

"I got into it after the war, quite by accident. I went to New York to see the play; Frank Fay had been playing Elwood P. Dowd for quite a while.

"During the intermission, the producer, Brock Pemberton, came up and asked what I thought of the play. I said, "I just think it's the most wonderful thing I've seen in my life.' He said, 'How'd you like to play it?' I thought he was kidding, but I said, I'd love to.' In three weeks I was playing it."

After three years in the play, Fay wanted a vacation, and Stewart was delighted to substitute. Pemberton invited all the drama critics to cover the new Dowd.

The result: "I've never gotten such bad reviews."

Stewart returned for another Fay vacation the following year. Again the critics were invited. "The reviews were even worse than what I got before," he said.

Undeterred, Stewart continued playing the role, and years later, when he was a better fit for the age of Elwood P. Dowd, he revived it in New York and London, with Helen Hayes as Dowd's dismayed sister.

Stewart discovered a regular pattern at the Saturday matinees. Parents would bring their young children, and inevitably in the first act one of them would call out, "Where's the rabbit?"

"That was always the biggest laugh in the play," he said.

Chase declared Stewart her favorite to star in the movie version of "Harvey," and a deal was struck. However, the actor had a certain reluctance.

"I wasn't sure about the movie. To me the whole idea is that you have to convince the audience that there is a rabbit up there with you, and you're talking to him. With the movie you have no audience; you have a camera, you have electricians, you have another set next to you.

"So it seemed different, and I didn't know if it would work. But the thing is strong enough so it did work," the actor said.

Elwood is among Stewart's most popular roles.

"In this world you must be oh so smart or oh so pleasant," Elwood says of his unflappable geniality, and that sums up the sweet comedy.

Even Stewart has said his portrayal was too nice. He brought out more haunting aspects of Elwood in later appearances, including a 1972 television production.

Jimmy Stewart at 82 no longer makes movies, but he remains busy, flying around the country to receive honors, appear for worthy causes and to talk about his book, "Jimmy Stewart's Poems."

The slender volume, containing a total of four poems, has sold 350,000 hardcover copies. The paperback, due later this year, is expected to zoom over 1 million.

"Johnny Carson had a lot to do with it," he said. "I recited the poems on his show, and I had some encouragement from (screenwriter) Leonard Gershe. He talked to some people in New York. They said, 'You just have four of them?'

"I love the idea when people say, 'When's your new book of poems coming out?' It took me 20 years to write these four poems. When I write another book, I'll be 102 years old. So I think I'm going to leave the thing. This'll be my book of poetry."