Someone asks rhetorically how old Bobby Kennedy will have to be before people will call him "Robert." He only lived to be 42. He is Bobby forever.

If he had lived, he would be 65 today, and so HBO offers a touching commemorative called "Bobby Kennedy: In His Own Words" tonight at 8, with replays on Nov. 24, 26 and 28. Those still susceptible to the mythic charisma of the Kennedy name will be warmed, cheered and moved.

As with producer Peter W. Kunhardt's "In His Own Words" documentary on Bobby's brother John, which HBO first showed in 1988, the story is told without a narrator and using a good deal of unfamiliar film footage, much of it showing Kennedy family home life. As a child and a young man, Bobby romps with his brothers and then, as a father himself, cavorts with his own kids.

Introduced at a speaking engagement by an offscreen voice as "the Boston terrier who barks -- and bites," Bobby was known for his tough, unrelenting combativeness. But the Bobby Kennedy one sees most in the film footage looks bashfully boyish, mild-mannered and self-effacing, Irish eyes plaintive even when smiling.

Many of the home movies are in color and show Bobby dancing, running, even standing on his head. The football, of course, is omnipresent -- he even tosses one from a campaign car during a political parade. There is also a shot of him rafting with a bulldog.

Equally rare are outtakes of commercials he made in 1964 during a successful bid for the Senate. The Kennedy wit was called into play during the campaign, when he laughed at his own accent and shared a podium with mother Rose, apparently one of the great upstagers of all time. She told one crowd, to Bobby's obvious chagrin, "I used to spank him with a ruler."

Turning to the driver of a car as it speeds along a New York highway soon after the election, Bobby Kennedy asks, "Am I a senator now?"

Two pieces of recurring imagery prove especially pungent: Bobby Kennedy's hands, which are grasped by the faithful on motorcade routes and which reach down to touch the faces of impoverished children during a tour of the deep South; and the rapt, adoring looks in the eyes of those who turn out to cheer and ogle Kennedy throughout his political career.

You see a hopefulness in those eyes that is rarely encountered now. We did not lose our innocence in the '60s but we gained our cynicism.

Typical of those who crowded the streets, a thrilled woman rushes out from the sidelines to snap a flash picture of Kennedy as he is rushed by in a car. The crowd at the 1964 Democratic convention applauds and cheers him for, by a commentator's estimate, 13 minutes and counting.

And then, much later, as Bobby Kennedy's funeral train makes its way down the East Coast from New York to Washington, among the thousands assembled along the tracks to watch it pass are a Little League team whose members stand in sorrow with their baseball caps held respectfully over their hearts.

The program is uncritical of Kennedy and his policies and is not meant to be an all-encompassing review of his political and personal life. It's meant to be an emotional experience, and it is. The spirit it evokes is one of feisty vitality, of determination and sacrifice and of struggling to make a difference.

Bobby at the Berlin Wall, Bobby in South Africa, Bobby in Brooklyn, Bobby in Georgetown, Bobby at Hickory Hill with Ethel and the clan. In an interview, he recalls assuring Martin Luther King Jr. during one of the most violent nights of the civil rights struggle that "we were going to keep him alive." A few years later, Bobby was the one to tell a crowd that had assembled to hear him in Indianapolis that King had been assassinated.

In Bobby Kennedy's 42 years, much history was lived and much passion expended. Also much energy. After climbing Mount Kennedy, named for his dead brother John, in the Yukon Territory, Bobby said, "I'm glad I did it, and I'm glad that it's over."

This documentary, which races through the years nimbly and evocatively and without undue sentimentality, makes it possible not only to relive the era and its moments, but also to gather along the railroad tracks once more and pay another tribute -- to be glad and grateful for the time we shared, and to stand again with a baseball cap held respectfully over one's heart.