Gary Hart is one presidential candidate for whom the end of World War II was not a time for decision: he was only seven years old. He remembers riding from his home in Ottawa, Kan., to Denver in 1944 on a train loaded with soldiers. But his father was not in the service, and Kansas was about as far away from the war as you could get; he remembers his childhood as "something out of 'Happy Days'."

Ottawa is 60 miles west of Kansas City, on three railroad lines; his mother's family were almost all railroaders, while his father's folks were cowboys. The farmland around Ottawa is more diversified than the western Kansas wheat country, and "there's a little topography." Still, when you get past the town streets with their shade trees you're in wide open country, where the farmhouses are exposed to the sun and rain and were only beginning to get electricity when Hart was born in 1937.

His father, who started off in farming and ranching, went into the farm implement business and sold equipment and machinery, and the family moved from the poorer side of Ottawa north of the river to the better-off south side while Gary was in grade school--just about the time the war ended. Later, when he was a teen-ager, the family name was changed from Hartpence to Hart. It was always assumed that Gary would go to college. He was a good student in high school, edited the newspaper, read a lot, and was involved in "almost all sports -- football, track, tennis."

Hart's family was not especially interested in politics. They were Eisenhower Republicans in the 1950s, and "one of the things that struck me was that they were against bigotry and prejudice. You just didn't discriminate against people." They were much more interested in religion. They belonged to the Church of the Nazarene, a conservative denomination that split off from the Methodist Church; they held offices in the church and taught in the school. And when Gary went off to college in 1954, it was to Bethany Nazarene College, a small school in Oklahoma City.

His experiences there seem to have shaped his political attitudes less than his summer jobs working on railroad gangs that straightened rails, which could be dangerous: "If a railroad crew didn't read orders, you'd really have to scramble." He found "very wise working people" there, "who had a lot to say about their bosses, sometimes not too polite." And he met people who had known harder times. "You could always tell a Depression guy. He'd be scared to death he'd lose his job, and he'd work his tail off." Hart worked on gangs that were 90 percent black and Hispanic, and one summer worked with a group of Navajos. It was a new exposure to another side of the prosperous, pious white Kansas farm country he had known since his childhood.

Hart entered college drawn to religion and philosophy, and he soon became a prot,eg,e of assistant professor J. Prescott Johnson. "He was the dominant influence on my life." Hart's parents may have hoped that he would become a Nazarene minister in a town like Ottawa, but under Johnson's guidance his career took a different turn. He edited the school newspaper and was elected student body president. He also did things other students didn't. "Prescott encouraged me to go on, and in late winter I applied to Yale Divinity School--the only school I applied to. No one at Bethany went to the Ivy League. But in April I was accepted."

He was married the summer after his senior year, and two weeks later he and his wife, Lee, drove to New Haven. He had never been east of Indiana, and "I had an idyllic notion of what it would be like. It was a grimy industrial town and it really startled me." They lived in a tiny apartment, and Hart, enrolled in the divinity school, became interested in American literature, taking courses from R. W. B. Lewis and Cleanth Brooks. He loved Tolstoy and Faulkner, but after his third year he decided he didn't want to teach, and so he audited courses at the law school and then applied and was accepted there. His classmates included future politicians Jerry Brown ("pretty reclusive") and Jack Danforth. It was about this time that Hart first became active in politics. By late 1959, he says, he was knocking on doors and handing out Kennedy literature; he worked out of an upstairs office with the party regulars in New Haven, although political activity--and Democratic affiliation--were not the norm at Yale then.

In 1964 Hart graduated from law school and joined the honors program in the Justice Department in Washington--another new city. There he worked, improbable as it seems now, on national security cases. Later he got a job as personal assistant to Interior Secretary Stewart Udall. "We got involved in more things--oil shale, appeals to the Supreme Court, antitrust and the lease for RFK Stadium." He remembers working on the first draft of the clean- water laws and on clean-air legislation as well.

That gave him the background to get a job with a Denver law firm after Udall left office in 1969. But it was not the first time he had thought of moving to Colorado: he had taken the bar there in 1965. It seemed a logical enough place. He had relatives there, and he had been going there since he was a kid. He got involved in politics as soon as he moved to Colorado, but claims he wasn't thinking of running for office, and in 1968 he left his firm and opened his own law office. He shared space with Craig Barnes, who was also part of the group of environment-conscious young liberals who were to take over Colorado politics in the next few years.

It was not too many months later, in March 1970, that George McGovern recruited him for his 1972 presidential campaign--the incident that begins Hart's book, "Right From the Start." McGovern, who had never met Hart, asked him to advance a one-day visit to Denver, and at breakfast the next morning asked him to head his national organization. Hart, interested in building up his Denver law practice, demurred, and instead agreed to organize efforts in 24 western states. But by June he was accompanying McGovern on an early trip to New Hampshire, and on that weekend he agreed to run McGovern's Washington campaign office--a commitment for the summer that lasted through November 1972.

Hart surprised many observers, once he had returned to Colorado and won a Senate seat, by not taking what they considered McGovernish stands on all issues. In his first term he became interested in military issues; he was less interested in cutting defense budgets than in developing winning military strategies. After he was reelected--one of two seriously challenged Democrats to survive the 1980 Senate races-- he signed up in the Navy Reserve. For Hart this represents not inconsistency but growth. He is much more interested in the military challenges the country faces than he is in refighting the Vietnam War, more interested in understanding the way the world he now sees about him--as "startling," perhaps, as industrial New Haven once was for him--works and how it can be improved than in continuing to talk about the remedies he advocated in some previous campaign.

"The situation is new in almost all respects," he writes in his recent book, "A New Democracy," and though he is talking about the economy today, he could be describing how the world has looked to Gary Hart--and perhaps how Gary Hart has looked to others--at each of the sharp and unpredictable turns in his life. The bookish high school student in the strongly religious household has changed, again and again, and while he's willing to talk about his past, it's plain that he's much more fascinated with the world he lives in today and the future he sees coming into being.