Under towering ficus trees there was talk of Alexander -- loard of the Attic Peninsula, Egypt, the land eastward to the Indus Valley and, as of last night, the National Gallery of Art. That's where the treasures of a royal tomb from his era are being displayed in a splash of publicity.

There was less talk of Ronald Reagan -- conqueror of the White House. And there were few Republicans of not wafting through the elegant dinner last night -- served by a score of white-gloved, tuxedoed waiters -- to kick off the exhibit "In Search of Alexander."

But there were many figures representing the powers that were.

"Hey Sol, how are you?" said longtime Rep. John Brademas (D-Ind.), who just lost his bid for reelection. The president's Middle East negotiator, Sol Linowitz, had put his arm around Brademas' shoulder. Linowitz shook his head soberly and patted Brademas on the back as they talked. Sen Paul Sarbanes (D-Md.) joined the huddle.

"It was one of those landslide things," said Brademas calmly."Nothing you can do about it." Brademas does not know what he will do next. "I have to consult with my wife the doctor," he said, gesturing toward Mary Ellen Brademas, who is doing her residency in Baltimore.

Brademas was a strong congressional proponent of the arts. "I hope President Reagan will give the arts strong support," he said, then added, with hope: "He comes from Hollywood."

In another huddle stood Rep. Sidney Yates (D-Ill.), like Brademas an influential congressional arts supporter. Yates was reelected. "Very sad," said Yates. "We've lost a lot of good men."

In Yate's group was National Endowment for the Arts Chairman Livingston Biddle -- who has one more year in his term as chairman -- plus Bernard Koteen, a National Symphony Orchestra board member, and Deborah Sale, deputy chairman of the Federal Council on the Arts. Sale will probably be out of a job.

"Those things happen in politics," she said. "But the thing you have to remember is -- you always come back."

"Unlike most of these youngsters I have a place to go back to," said White House counsel Lloyd Cutler, referring to his old law firm of Wilmer and Pickering. Cutler was in London during the election, "which mad it less painful," he said.

Linowitz characterized himself as "surviving." He said, "I'm going back to conducting my life the way it was before." But he's a man used to transition. "If I can help out, I will -- I've known George Shultz and Caspar Weinberger and Kissinger."

But for those with art in mind politics mattered little.

The Time Inc. people were happily gazing at the exhibit I. M. Pei was happily gazing up at the roof of the National Gallery's East Building, which he designed. "I'm just as happy not to come here frequently," said Pei smiling. "You want to let time take care of the building. Well, It's too late now anyway to change anything."

Among a contingent of officials from Greece who were toasted and applauded for their help with the exhibit was Manolis Andronicos, the Greek archeologist who discovered the Macedonian tomb from which many of the artifacts came. "In the winter we stop digging," said Andronicus, who has been at it for 40 years. "We only dig in the summer."

Joseph Hirshhorn, donor of the art in the Hirshhorn Museum, took in the awesomeness of the Gallery. "I wish I were rich instead of short," said Hirshhorn who is, of course, both.