It was 50 years ago, on a cold, gray March Saturday in Washington, when Franklin Delano Roosevelt took the oath of office that launched a revolution in American government, and today they gathered here, loyal veterans of the New Deal, to talk and celebrate and reminisce about a man whose legacy still casts a shadow over all who have followed.

It was a day of what someone called "the flavor and the fervor" of the New Deal, a chance to share old memories and anecdotes of what Lady Bird Johnson called "those vigorous days of our youth," and to try, as best they could, to understand what Roosevelt meant not only to them but to the entire country.

By accident or design, it also was a day of continual references to the presidency of that one-time New Deal devotee and Roosevelt supporter, Ronald Reagan, whose administration has been seen as a direct assault on the FDR legacy.

What brought everyone together was a three-day symposium--jointly sponsored by the Lyndon Baines Johnson Library here, the Franklin D. Roosevelt Library, the University of Texas and Virginia Commonwealth University--called "The New Deal Fifty Years After: An Historical Assessment." It was timed to coincide with the 50th anniversary of Roosevelt's first inaugural March 4, 1933.

Some of the participants were players in those early, heady days in Washington, days that Wilbur Cohen, who came to the capital from the University of Wisconsin and later served as secretary of Health, Education and Welfare, recalled as "the most thrilling experience of my life."

Others were observers, reporters and historians, who recalled the energy and excitement of Washington at the time. "The New Deal days in Washington were unbelievable," said reporter Esther Van Wagoner Tufty, "just unbelievable."

The sense of hope that Roosevelt brought to many Americans was recalled vividly by others who watched Roosevelt from afar, praying he would succeed. One was Helen Fiser Myers, who was a teen-ager in Arkansas and saw her father's farm and home repossessed when the banks closed in the spring of 1933. "We lived for Roosevelt," she said.

There were lighthearted and poignant memories, especially from Roosevelt's son James, now 75, who recalled the 15-minute violin solo by Roosevelt's secretary of the Treasury during the first long night in the White House as the new administration wrestled with the problem of the banking system, and who later said of his father, "I think of him as a human statesman, but most of all as a beloved father."

There also were moments when certain other legacies of the Roosevelt years--the development of the atomic bomb and the internment of the Japanese-Americans--also were recalled.

A sense of the present hung over the gathering today, a feeling fueled by Gerald Carmen, Reagan's General Services Administration chief, who, to the audible grumbling of the audience, linked FDR to Reagan by saying the New Deal was "not unlike" President Reagan's New Beginning, and that Reagan is "offering the same kind of leadership" that FDR offered during the Depression.

And while many members of this morning's panel on how the New Deal began confined themselves to joyful moments of the 1930s, economist Leon Keyserling used the opportunity to declare that "our great America has been sliding downhill since the end of World War II" and that what one "has to learn from the New Deal is not academic generalities in how glorious it was, but what do we do?"

But the symposium was principally an attempt to put Roosevelt into proper historical perspective, and it was given to economist John Kenneth Galbraith to describe to the audience of nearly 1,000 the meaning of the beginning of the New Deal.

Galbraith said Roosevelt led "the great transition in modern capitalism" to a system that attempted to protect those who were suffering. Roosevelt, he said, had no grand design for how to attack the Depression, only an ability to select the best available ideas and the energy for action. FDR had, said Galbraith, a joy of battle and an ability to extend to the American people a sense of community.

"He did not speak as a leader to his followers," Galbraith said. "He spoke to participants as a participant."

James Rowe, Roosevelt's administrative assistant, recalled being asked by historian Arthur Schlesinger Jr. if Roosevelt truly understood the many programs he helped push through Congress. Rowe said he told Schlesinger he didn't know about that, "but I do know he knew how to be president. He never had to ask anybody how to be president."

Inevitably, here in the home of Lyndon Johnson, there was much talk of Johnson's days as Roosevelt's "pet congressman," as Virginia Foster Durr, who fought the poll tax after coming to Washington during the New Deal, put it--and talk also of how FDR's presidency influenced Johnson's.

"Lyndon Johnson wanted to do a great deal more than to carry out the Roosevelt tradition," said historian William E. Leuchtenburg. "He wanted to exceed it."

But it was Leuchtenburg, in his assessment of the effect of Roosevelt on succeeding presidents, who declared that Roosevelt's long shadow is beginning to pale. "It seems clear that no one will any longer live in his shadow," he said. "But it will be a considerable time still before it vanishes forever."