Ronald Reagan, making his first appearance on the world stage as a peacemaker, seemed out of sorts.

It was almost as though he hated himself for being thrust in a new, unfamiliar and uncomfortable role. He showed a grim face to the U.N. as if to compensate for being, in spite of himself, about to make accommodations with two nations he has spent the last seven years warning the world about.

It was hard to find in his speech any elation about his recent decision to "conclude" a treaty on intermediate- range nuclear missiles in Europe.

It was impossible to detect any hint that he may be on his way to doing business with Nicaraguan President Daniel Ortega.

Although he abstained from the rhetorical excesses of other years, he couched his review of the state of the world in terms that almost forbade contemplation of the fact that he has taken an irreversible step in ending the Cold War.

He gave the Soviets fair warning that the West is on the wing, that democracy is an irresistible force: "Those who advocate statist solutions to development should take note -- the free market is the . . . one true path. To those governments I would only say that the price of oppression is clear. Your economies will fall farther and farther behind. Your people will become more restless."

Hardly the stuff of summit chitchat.

Have the Soviets changed from the scoundrels he named in his famous 1981 onslaught about leaders "who reserve unto themselves the right to commit any crime, to lie, to cheat"?

Apparently not. He published their treachery in the Persian Gulf, their false accusation that the United States is the "source of tension in the gulf."

He lit into them about Afghanistan. He repeated his demand for a deadline on withdrawal, as per Gorbachev's declaration of intent. Grandly he told them that if they show "convincingly" that they are ready, "the U.S. is ready to be helpful."

Uncle Sam still has to show the Soviets how to act, how to achieve "constructive" conduct in the drawing rooms of the world.

As for Nicaragua, his other obsession, it is still a pariah nation. The fact that it is doing what he never expected it to do does not fool him for a minute. On the eve of his U.N. speech, Ortega gave La Prensa permission to publish again. Reagan is not taken in.

He had high, and not necessarily accurate, words about the contras. They "operate freely deep in your heartland," he told the Sandinistas.

"Understand this," he said sternly to Ortega, in case anyone would think he was mollified by the liberation of La Prensa, "We will not, and the world community will not, accept phony 'democratization' designed to mask the perpetuation of dictatorship."

The United States is still in charge of the world, said the man who has just announced that we will trust the Soviets to observe an arms treaty.

"Freedom in Nicaragua or Angola or Afghanistan or Cambodia or Eastern Europe or South Africa or anyplace else on the globe is not just an internal matter," he declared.

His roll call had one conspicuous gap: Chile, which has been savagely oppressed by its dictator, Gen. Augusto Pinochet. He can do what he likes. But the great connoisseur of democracy remains silent while the general runs for election by a terrorized electorate.

Moscow and Managua may not be too upset by Reagan's curious debut as a dove. They may understand that Reagan, who has taken one small step for arms control but one giant leap for better relations with Russia, is desperately trying to reassure his core constituency that nothing has changed.

He cannot admit what he has done. He has put a foot in the door. More talks, more agreements are inevitable. Nor can he admit that progress on arms control was the only way he could extricate himself from the mire of the Iran-contra scandal and the awful backwater of irrelevancy.

He may not be the president to do the negotiating on the heavy stuff, the reduction of the strategic nuclear forces, but he has made it respectable, perhaps mandatory, for a successor to go straight to the table.

He has given people a glimpse of what can be. Now they have seen that even Ronald Reagan can talk to and deal with the Soviets, they will not let him turn back to the Cold War. It's trickier with Nicaragua, but again the vista of a peaceful political solution has been seen. Who wants to go back to guns?

Reagan has not so much repudiated his past as he has had repudiation thrust upon him. No wonder that he appeared before the United Nations, in the words of A.E. Housman, "a stranger and afraid in a world I never made."