What is sadder than a beautiful woman dying young? Natalie Wood was able to remain a beautiful young woman through three decades of fantasy on the movie screen. Yesterday, her body was found floating in the Pacific Ocean off Catalina Island.

When a movie star dies, all kinds of memories well up -- not only of screen roles and whatever part of the star's private life went public, but also of ways these distant visions and separate lives interacted with our own. In the '50s, Natalie Wood was an ultimate idealized teen-ager to girls who wanted to be like her and to boys who may have found in her one of their first raging erotic fixations.

She stayed beautiful, she stayed gorgeous; she was never anything so minimal as merely a sex symbol, and yet it would be hard to sustain the contention that she was a great actress. Like others who make mysteriously indelible impressions on the mind and dream-life of the mass audience, she was a great movie star -- on occasion, a scintillating presence, and Hollywood royalty for the first rock 'n' roll generation.

And even though millions grew up with her, and watched her grow up on the screen, she seemed incurably youthful and, at heart, incorrigibly naughty -- the good girl with the bad girl inside. Her death at the age of 43, apparently by drowning, seems all the sadder and more of a cheat because of that youthfulness, and yet it ensures that there will never be a photographic image of her, anywhere, in which she looks old or spent or without that teasing insouciance.

Movies can bestow not only immortality of a sort, but eternal youth of a sort.

Although not a particularly potent box office force in recent years, Miss Wood remained within the peripheral vision of the public eye, and repeatedly would snap back into focus. In a 1979 NBC remake of "From Here to Eternity," she was the principal and perhaps sole source of electricity as she played the sex-starved wife of an Army officer at Pearl Harbor in 1941. Her dark Russian eyes were beckoningly provocative, and the film's first scene was one in which she sauntered teasingly across the Army base, followed religiously by men's admiring eyes.

She could still be the best of the bad girls.

Miss Wood made the transition not only from child star to national teen-ager, but from ingenue to leading lady. In the '40s, she appeared to be 20th Century-Fox's answer to MGM's enormously popular Margaret O'Brien when she played the trusting little girl who melts a cynical mother's heart in "Miracle on 34th Street," the Santa Claus movie now making its annual holiday appearances on local television (Jack Albertson, also recently deceased, has a small role as a post office worker).

Then, in the mid-'50s, she played the teen-ager fascinated by the enigmatic broodings of James Dean -- a surrogate for all the girls in the audience -- in "Rebel Without a Cause," which galvanized a generation and helped give it an identity. She looked up at Dean with the same worshipful eyes with which she'd looked up at Santa, but now there was something new in them.

By the time of her best film, "Splendor in the Grass" (1961), she was ready to leave the ranks of adolescence with one last histrionic display -- a sensational bathtub scene in which, as a love-struck high school student, she responds to her mother's obsessive anxiety over her virginity with shrieks and splashes and shouts. It was a shocker, especially after a series of innocuous roles. The film was set in the past, but it and the performances confirmed to every kid who saw it the great truth of youth: that adults know nothing about love.

In 1976, Miss Wood and her movie-magazine husband, Robert Wagner, visited Washington to promote an upcoming TV production of "Cat on a Hot Tin Roof" in which they appeared with Laurence Olivier. It was a terrible show, but Miss Wood looked magnificent in a silk slip as Maggie the Cat.

In their hotel room, the couple, who had once divorced and later remarried (as if to obey a plebiscite of movie fans), ate gooey reuben sandwiches and talked in pleasingly superficial terms about their lives and careers. They radiated well-being and the Hollywood version of class; they still seemed entranced by how well they looked together and how their romance had assumed the storybook qualities of a romantic movie.

Miss Wood wore a white suit that day, and gold chains around her neck -- from one of which dangled a plump red heart -- and her deep brown eyes were completely outlined in black, so that they were the first things you saw when you walked into the room, and would have been even if a brass band had been playing in one corner. There was chit-chat about family life in Beverly Hills and about show business. Miss Wood was saucy, and shiny, and down to earth.

She said she couldn't remember all the films she had made, especially those of her childhood. "Even though I don't really remember 'Tomorrow is Forever' 1946 , I remember Orson Welles and Claudette Colbert very vividly," she said, smiling. "Tab Hunter and I did one called 'The Burning Hills,' and I had to do this hilarious line lapsing into a mock-Spanish accent , 'You doity gringoes! You turn dis town into a scorpions' nest!' " She laughed. "That makes us break up so much, we'd hate to see the movie disappear."

And she recalled having just shown "Miracle on 34th Street" to her own children, denying a published report that they'd hated the film. "No, they just got a little bored. The only people terribly moved by it were our parents. When the lights came up, there were tears streaming down their cheeks." Wagner was asked then if there were anything about his life with Natalie Wood that he would like to change. He said, "Not a thing that I can think of."

It's going to be awfully hard now to watch reruns of "Splendor in the Grass" on television and not get even more depressed than the movie is supposed to make you anyway, especially in the last scene, when Miss Wood's voice on the soundtrack -- over a shot of her walking away, smiling bravely, from the great love of her life -- recites again from Wordsworth:

"Though nothing can bring back the hour, of splendor in the grass, of glory in the flower; We will grieve not, rather find strength in what remains behind."

Alas, we have lost a knockout.