A BRAZILIAN journalist who has long been stationed in the capital of this comfortable country returned to his homeland for a rare visit and was pleasantly startled by the changes. Brazil, if you have forgotten, is not exactly famous for civil liberties, free speech, free press, free politics.

But he found things were improving. The government censorship was more relaxed. The fear that an unorthodox opinion would lead to arrest and prison was considerably reduced. He saw real progress.

And something else which startled him. In the newsroom of an important periodical, he saw Jimmy Carter's picture on the wall. Yes, Jimmy Carter, the scorned president, was a hero in a Brazilian newsroom. Perhaps it was a droll gesture, but my friend, the journalist, thought the meaning was clear. The reporters and editors knew Jimmy Carter's preachy pronoucements on "human rights" had something to do with the increased freedom in their own newsroom.

Well, those sermons are gone now. Our allies will no longer have to suffer through wimpish lectures from the president. The next president promises "strength" as the single code word for his foreign policy, which is actually a restoration of the old foreign policy that America pursued in the world for 30 years. "Human rights" is a yawn, yesterday's indulgence. The Washington Spring" is over.

The "Washington Spring," as I define it, was a brief and fragile experiment in revisionism, an interlude which can be precisely dated. It began with the fall of Saigon in 1975 and ended, for all practical purposes, with the Russan invasion of Afghanistan last winter. In between, there were many emblematic events expresing fitful effots to define a new approach to the world:

The Congress refused to permit military engagement in Angola. The executive resisted the temptation to intervene in Somalia. The Central Intelligence Agency was severely restricted in its overseas manipulations and secret interventions. Congress asserted long-neglected powers of oversight and consultation. The president preached a different message, a sermon of America's moral strength in the world. He began grading our friends and allies on the basis of their own behavior, their allegiance to the principles of human rights which we embrace. He attempted, with meager results, to redefine global problems outside the traditional scheme which had sustained American policy since World War II -- the world struggle between two empires, the Soviet one and ours, a Cold War in which there is no neutral ground, no unimportant battles.

Strictly speakiing, Carter's revisionism collapsed in Iran, trapped in its own contradictions. He was unwilling to abandon the old neocolonial relationship with the shah's government and unable to engineer a transition to the revolutionary future. The Russian occupation of Afghanistan, though it resembled in some ways the U.S. occupation of the Dominican Republic in 1965, was the final confirming event. The revisionism was wrong, naive, doomed. Now the Cold War struggle must be revived. The recent election returns seem to be a full-throated endorsement from the people.

We will learn soon enough how the policy of "strength" copes with complexity; I suggest modestly that Americans will discover, all over again, that "strength" creates its own version of naivete and its own contradictions. President Reagan, for instance, promised the farmers of the Middle West that he will the U.S. grain embargo just as it is beginning to threaten the Soviet Union with truly grave consequences. How can he keep that promise to American grain farmers and at the same time impress the Red Russians with his toughness? What will he do to Iran if, as now seems possible, the American hostages are still held in Tehran by inauguration? Or, if the Iran-Iraq war continues, how will he prevent the threatened return of gas lines and soaring prices in the United States?

None of these time bombs will be defused by rhetoric; none of them will be resolved by merely increasing the U.S. defense budget. Perhaps the CIA, unleashed to resume an activist role in foreign affairs, will discover secret solutions. Or perhaps we will learn, once more, that secret solutions are not compatible with democratic consent.

But that's in the future. The question right now, stated in sympathetic terms, is why did the revisionism fail? The "human rights" apostles outside the government frequently blame Carter's inconstancy or inept execution, though even they concede that a president cannot unilaterally rearrange all of America's complicated foreign relations without enduring some contradictions. aOthers argue, with valid examples, that it wasn't failing -- that the new U.S. policy in Southern Africa and Central America, for instance, demonstrated that the transition to post-colonialism is possible. Only they ran out of time and out of popular support.

But let me suggest another explanation: The use of "human rights" as the emblem of revisionism was profoundly misleading, even hypocritical, as its critics always said, for the "human rights" campaign masked the real historical argument that was at stake. It pretended that America's interest in world affairs was grounded in moral principles, not in the crass motivations of self-interest. But as Joan Didion has observed in another context, morality originates in self-interest, in the healthy moral imperative of survival.

The hidden argument is about empire. Shall we abandon the idea of an American empire? Can we? That's what the "human rights" slogan implied, but it failed to make the hard-headed case for American self-interest. Iran and the fall of the shah offered a classic study on why the long-term consequences of empire are so bleak for America, but no political leaders dared to teach the lesson. So we will have more Irans and Americans will continue to be angered and confused by events until they grasp that our true long-term survival depends on recognizing the changed nature of the world, on abandoning imperial follies.

Most Americans, of course, do not think of themselves as imperialists, but we are not talking about Caesar's legions who capture territory and rename the towns for the conquering heroes. We are talking about economic and military domination, a network of alliances and dependencies which presume U. S. benefits and obligations far beyond the necessities of our national security. Empire does return benefits -- i.e., a generation of cheap oil from the Middle East -- and it also extracts huge costs -- i.e., the lives and treasures spent in Indochina to demonstrate our global "strength."

But if there is an American Empire, albeit without maps and boundaries, are Americans willing to abandon it? The political answer seems clear but the question was never clearly put.

Many of the "human rights" advocates were less than straightforward about their objectives. They did envision -- many of them, but not all -- a post-colonial foreign policy for America, one which assumed a future based on parity, not dominion. Perhaps so did Jimmy Carter. But these advocates were most elliptical in explaining that hidden question of empire of arguing that it would serve America's long-term self-interest beyond satisifying the goo-goo principles. Carter's foreign policy, in the end, tried to have both ways in various parts of the world, to pretend that America would evolve toward a more benign status as partner, not sponsor. But in most crises, whether in Iran or Korea or the Phillippines, the Carter policy swerved back to the safe ground of faithful patron.

The cold warriors would argue, of course, that America has no choice in the matter except to struggle or to face defeat. It must stand up to the Soviet empire builders or stand by and watch the world slip under Communist control. The revisionists would argue that historical forces are moving simultaneously to undermine both empires, that so long as the United States interprets events in terms of empire-vs.-empire it will continue to be surprised and confounded by uncooperative history.

Empire, theirs and ours, is threatened by at least three new realities in the world. Our old friends, the Europeans and the Japanese, have come close to achieving economic parity with us and are delighted to compete head-to-head with their former guardian, Uncle Sam. The resource nations, meanwhile, are discovering the strategies for renegotiating the flow of benefits between us and them, a fancy way of saying that the days of cheap oil from the Middle East are gone.

Finally, the global operations of multinational corporations are confusing, even obliterating, the old assumptions of imperial boundaries. The multinationals' goal is to rationalize the organization of world resources, production, markets; they are most unsentimental, about respecting national soverignty or ideological alliances.

But if empire cannot endure in this world, at least with its old prerogatives, what will replace it? William Appleman Williams, the revisionist historian, draws a provocative and gloomy formulation of American behavior, one which I can't quite buy myself, in his essay, "Empire as a Way of Life" (Oxford University Press, 1980). Tracing the great sweep of American development, the westward conquest of the continent, the idea of Manifest Destiny in foreign policy, Williams wonders if America's democratic faith can survive without the sustaining idea of empire.

To oversimplify his argument, Williams describes an ever-expanding America, drawing on others' resources and continually developing new pools of economic activity, as the guarantor of the American promise of equality and opportunity. If one accepts a future of limits in which future growth is no longer believable, then Americans would have to satisfy those promises of equal justice internally, facing domestic questions which have always been evaded by the vision of ever-expanding growth and new wealth. New frontiers, as John F. Kennedy put it, talking about the global struggle with communism.

Certainly, American voters spoke clearly enough on this question. They want growth, strength, new frontiers, not limits, not parity. Viscerally, as an American, I am with them. In my head, however, I wonder about those Brazilian journalists and whether or not my own self-interest, in some distant manner, is not tied to theirs.