After a hard day talking about crises in the arts, the talkers left their briefing books behind at the Four Seasons Hotel (where the National Council on the Arts was meeting) and headed over to Livingston Biddle's Georgetown house for early evening cocktails.

Beverly Sills, director of the New York City Opera, on her way out of Biddle's, chatted with Rep. Sidney Yates (D-Ill.) on his way in. "Come by Wolf Trap for the New York City Opera's 'Student Prince,'" she entreated him, red hair glinting in the Saturday sun.

When Yates finally made it up the stairs into the house, he was greeted by applause and cheers fit for a warrior coming home after a successful conquest. In fact, the welcome was appropriate because while Reagan was proposing budget slashes, Yates managed to get a beefed-up appropriation for the Natonal Endowment for the Arts ($157.5 million) through the House. Biddle, chairman of the NEA, gave Yates a pat on the back as he walked in. Then, Minneapolis museum director Martin Friedman, of the National Council on the Arts, pulled Yates over to a corner of the living room for some serious talk.

No matter. The rest of the guests -- and what an amalgam of Hill people, ats names about town and country -- were still devoted to enjoying themselves on a hot, bright day. Luminaries like the National Gallery's J. Carter Brown, National Endowment for the Humanities' Joseph Duffey, architect I. M. Pei and museum donor Joseph Hirshhorn could all be seen wandering through the crowded house. In the living room, Debbie O'Callaghan played guitar, and on the porch a chartreuse mariner's parrot occasionally shrieked out from its cage. "He certainly was noisy," Catherina Biddle, wife of Livingston, said later. "He's not used to all those people."

In the thick of guests on the porch, David Morse, staff director of the White House Task Force on the Arts and Humanities, had doffed the serious bow tie and navy blazer he had worn to the Council meeting, and rolled up his shirtsleeves. Painter Jim Rosenquist, another National Council member, showed up clutching his red bathing trunks.

"Jim, let me show you where the pool is," said Catherina Biddle, escorting him away from conversation with Joan Mondale, beloved arts advocate who hasn't been seen much lately.

"ROGER!" exclaimed Yates upon seeing Roger Stevens, head of the Kennedy Center, back on the party circuit after his recent heart surgery. "How are you? Nice to see you!" Stevens was on his way to see "Annie" at the Kennedy Center for what must be his umpteenth time, as he is one of the producers.

"That's incredible," offered one guest, seeing Roger Stevens. "The man just had triple bypass surgery and he's bouncing around."

Not bouncing around was the White House's Aram Bakshian, who stood on crutches by the pool, chatting with National Counci member and actor Theodore Bikel, who was walking with a cane. "I was injured in the interest of art," Bakshian explained, puffing on a cigar. "I was doing a Cossack dance -- leaping upt and all that."