Two aging political warriors whose enmities have been softened by time chatted quietly in the Oval Office last week about a memorial to an American president whose legacy has enriched their lives.

The onetime antagonists were President Reagan and the man he retired from public office, former California governor Edmund G. (Pat) Brown. When Brown sought a White House appointment, he jokingly told the secretary that he was the man who had launched Reagan's political career.

The president, 74, talked amiably with Brown, who will be 80 next month. Brown, who has been a guest of five other presidents, used the occasion to seek support for a long-delayed memorial to Franklin D. Roosevelt.

Only a few years ago, Brown lacked respect for the man who had defeated him. Now he freely admits that he underestimated the skills and appeal of Reagan, whom he calls "the most remarkable politician I've ever known."

When Pat Brown calls someone a "politician," it is a compliment. But in 1966, when Reagan ran against Brown, who was seeking a third term as governor, he recognized that the public felt otherwise and called himself a "citizen-politician."

Their campaign was one of competing caricatures. Brown was portrayed as a bumbler who had mismanaged the state's finances and turned soft on crime. Reporters, once fond of Brown's gregariousness, mocked his mannerisms. We recalled that Brown, viewing the Eel River flood, had proclaimed it "the greatest disaster since I was elected."

Reagan also was stereotyped as a dim-witted actor who had been upstaged by a chimpanzee in the movie "Bedtime for Bonzo." Democrats described him as hopelessly out of his depth.

Reagan sometimes reinforced these perceptions. Addressing wood producers, he said, ". . . You know a tree is a tree, how many more do you need to look at?" Asked about the state's fair-housing act, Reagan said he could come up with an answer if he could sit under a nearby tree and think about it.

The caricatures did not define the men. Brown, a former Herbert Hoover Republican who became a Democrat after the coming of the New Deal, was one of the last successful big-state liberal governors.

During Brown's governorship, in the golden age of American liberalism, California became the most populous state. It led in building great universities, modern hospitals, a mammoth water project and a freeway system that was the nation's envy. But it was also in California where cracks first appeared in the New Deal's foundations.

By the mid-1960s, campuses were in ferment over the Vietnam war, freeways were congested, air and water were polluted. Middle-class Californians were in revolt against a government that they believed taxed too much and delivered unnecessary programs.

Reagan was an active beneficiary of this frustration. Like Brown, he was a political convert, but one who had drifted from Democratic roots. Unlike some others, he never lost his reverence for the cadences and force of Roosevelt's speeches or failed to appreciate his mastery of the presidency.

Reagan turned the Roosevelt revolution on its head. He mobilized the creative political energies of Americans and rekindled their optimism by leading a crusade against government. Far from being empty-headed, he was intuitively in touch with the spirit of his age, as Roosevelt had been.

But in separate ways, the two politicians overstated the optimistic values of the New Deal. Brown did not realize that a deficit-financed war and limits on what Americans were willing to do for their fellow citizens meant an end to the golden age. Reagan has not recognized that oversized defense budgets and deficit spending can undermine conservative agendas.

These ideas were not discussed last week in the Oval Office as the two gracious warriors talked inconclusively about the long overdue FDR memorial. One would hope that Reagan supports the proposal, if only in recognition that his own career and Brown's are impressive testaments to the rich and conflicting legacies of the New Deal.

Reaganisms of the Week: Speaking to the National Association of Counties last Monday, the president said: ". . . I couldn't help thinking that, if the definition of a good budget proposal is to distribute dissatisfaction, ours is a real winner."

Speaking to business leaders in the East Room last Wednesday, Reagan said: "Nuclear war would be the greatest tragedy, I think, ever experienced by mankind in the history of mankind."