When David Rockefeller's Trilateral Commission came to Washington last week and called upon the Carter administration, it was like the nest returning to the sparrows.

President Carter, an ex-Trilateralist himself, greeted his former brethren in the East Room with praise so generous that it was mildly embarrassing to some.

"I was dumbfounded by some of the things he said," said a Trilateral executive. "I would love to get permission to quote him in our fund-raising."

This is terribly off-the-record, like all Trilateral discussions, but Carter told the 200 movers and shakers from America, western Europe and Japan that, if the Trilateral Commission had been in business after World War I, the world might have canceled World War II.

Thus encouraged, the Trilateraists heard from three other alumni, the Cabinet officers who count most in global matters - State, Defense and Treasury. A fourth star canceled his briefing because of illness - Carter's national security affairs adviser, Zbigniew Brzezniski, the intellectual father of the Trilateral idea.

"Poor Zbig, he was sick as a pup," said Trilateral coordinator George S. Franklin. "He caught the Russian flu in China."

At least 18 top-level executives of the Carter administration were drawn from the Trilateral membership. So was the foreign minister of Japan. So were the prime minister of France and the labor minister of West Germany. The present membership includes 12 former Cabinet officers and top advisers of past U.S. administrations, from Kennedy's to Ford's.

It is a very heavy group - bankers and corporate barons, fellow-traveling technocrats, promising polticians and a light sprinkling of trade unionists drawn from three continents. This has stimulated much spooky theorizing about a Rockefeller shadow world government, a floating establishment conspiracy to run everything. In some circles of fervid political imagination, the "Trilateral connection" is shorthand for puppets on a string, responding to a secret agenda.

The reality, alas, is less dramatic. On paper, they run the world. But, in the flesh, the trilateralists get together and mostly talk about how the world out to run, if only the world would cooperate.

This humble little secret slipped out from under the mirror-paneled doors at L'Enfant Plaza where the Trilateralists met for three days last week: the heavyweight members, despite their awesome economic clout, feel defensive, uneasy, unloved.

"It's surprising," said one participant, "that these big, powerful, hefty tycoons would be so defensive. They are not terribly confident."

At the White House, even the president lectured them on their bad image. Three foreign leaders from Third World countries, Carter said, have told him personally that the Trilateral Commission is nothing but "a rich man's club" which doesn't care about the rest of the world. The Trilateralist, Carter urged should demonstrate to the poor nations of the world that the commission "has a heart."

"Ninety percent of the questions," one informed witness said, "were: 'Tell us, Mr. President, what can we do to get on better terms with the Third World?'"

It is a "rich man's club" global terms, but that was the idea in the first place. The members are drawn from the leading industrial and financial and intellectual empires of the noncommunist world - Citibank and Fiat and Nippon Steel, Oxford and Harvard and Tokyo University, Coca-Cola and Barclays of London and Mitsubishi. Their meetings are all in private, presumably to stimulate franker discussion, but perhaps also to enhance the mystique of importance.

At the Washington sessions, a number of participants noted how restrained and defensive the Trilateralists were with one another, tip-toeing around the strains and differences among themselves.

The Japanese were defensive about their trade surpluses. The Americans about their growing oil imports. The British and French about their import barriers. Their Germans about their low rate of growth.

This is not exactly what everyone expected when "Trilaterlism" was coined five years ago by Brzezinski as the new catch phrase of global thinking. It may have a short shelf life, as catch phrases go, because the Trilateral agenda has not exactly swept the world.

Neither the Carter administration nor its counterparts in Europe or Japan have been able to move very far on the monetary revisions proposed by a Trilateral study. Nor have they developed the unified energy strategy urged by the commission. Nor have they worked out a consolidated bargaining approach to those underdeveloped nations who are demanding a new economic order in the world.

The problem is messy politics, in every instance. And some of those who were inside note that the Trilateral talks here were stimulating and educational, but a trifle unreal - lofty theorizing above the realm of practical politics.

"They address serious problems in serious ways," said columnist Joseph Kraft, one of three journalists admitted as observers with the understanding that they would be discreet in reporting who said what. The others were New York Times columnist James Reston and Le Monde correspondent Michel Tatu.

"They're very useful for people who are not used to this world of discussion, but they are most distinguished for their ack of political realism," Kraft said. "They talk about the energy problem, but there's no acknowledgement of the political nationalism sweeping the world. There's no how-do-we-get-from-here-to-there."

John Sawhill, president of New York University, former federal energy administrator, and author of the Trilateral report on energy, made a similar point but saw a certain virtue in the commission's detachment.

"It's a little more detached from immediate politics," Sawhill said. "This gives the politicians a chance to step back and take a longer view of the future."

Richard Barnet, author of "Global Reach" and a leftist critic of multinational corporations who was definitely not invited to the Trilateral meetings, thinks the Rockefeller organization is increasingly irrelevant.

"It all based on a make-nice view of reality," Barnet said. "Most of the positive agenda hasn't got anywhere. It was most interesting in the pre-Carter period because it looked like a nesting place for the next Democratic administration, if there was going to be one. Now it is less interesting."

Indeed, many of the members themselves think the Trilateral gatherings - in Bonn or Tokyo or Ottawa or here - are less valuable for the ideas or consensus they strive to generate, more useful merely as get-acquainted sessions. The Japanese, in particular, were drawn into deeper relations with European leaders through the Trilateral sessions and are now engaged in regular government and private exchanges.

The attendance is good, especially when the meeting is held in Washingtn, because everyone knows the governments will be listening to what's said.

"These are influential people," said Maurice Sauve, former minister of Quebec. "They carry weight. If they want some action to be done, they can make the contacts without having to wait."

"Frankly," said Sawhill, "it's an awfully good training ground for American political leaders and not only American leaders."

Rockefeller and Brezezinski demonstrated a certain skill in picking ascendant politicans when they originated the commission in 1973 - tapping Carter and Vice President Mondale, long before they were close to the White House.

For what it is worth, Rockefeller's list of young and promising politicians recently added to the commission includes Rep. William S. Cohen (R-Maine), Sen. John C. Danforth (R-Mo.), Illinois Republican Gov. James R. Thompson and West Virginia Democratic Gov. John D. Rockefeller IV, who is David Rockefeller's nephew.

Tatu, the Washington correspondent for Le Monde, said the Trilateral meetings have a certain sameness to them. The same people show up for the Bilderberg Conferences and Atlantic Institute meetings, a fact which stirs the conspiracy theorists to spin intricate webs of interlocking power.

"It's no more or less imperialistic than any other meetings like this," Tatu said. "The leftists think its a big conspiracy, which is completely wrong. It's just a forum for talks, very often empty talks."

Sen. William V. Roth (R-Del.), one of 11 senators and representatives on the commission, discovered an ancillary benefit from his membership. Last year, Penthouse magazine published a lengthy expose of Rockefeller's shadow government.

"That gave me an excuse to buy Penthouse," Roth said.