So, if you're a painter and your great-grandfather was Claude Monet, does it help or hurt?

"Both," said Jean Marie Toulgouat, 58, the great-grandson in question, posing for the cameras in front of a painting of white turkeys -- one of Toulgouat's favorites -- by Monet, the great Impressionist painter, in the National Gallery of Art last night.

"It's easier to have contacts when you have roots that are a little known," he said with innocent understatement. "But it's very difficult with the critics." Toulgouat, who lives in Giverny, France, and paints nature studies that are part abstract, laughed at the obvious. "You see, I have nothing to do with Monet. I'm a painter from the 20th century."

Last night, the 19th-century Impressionist painters, who were once rejected by the established Paris salons only to be revered in the 20th century as some of the greatest and best known artists in the world, were glorified in absentia at a black-tie dinner at the National Gallery of Art, whose guests included ambassadors and politicians, curators and collectors and even a handful of the painters' descendants. The event was the museum's exhibition "The New Painting: Impressionism 1874-1886," which features gallery rooms draped with some of the world's most beautiful art.

"I never knew him, I never met him," said 21-year-old Sophie Renoir, the great-granddaughter of Pierre Auguste Renoir. "But -- how can I say this in English? I am happy to be part of his family. It's always nice to be part of a good family. You don't want to be part of a Frankenstein family."

The paintings are grouped according to the eight exhibitions the then-outcast Impressionists put together: "It's the first time you see an exhibition about the exhibitions," said Toulgouat.

But there's nothing outcast about these paintings now. And no one summed that up better than, interestingly enough, Secretary of Defense Caspar Weinberger. "It looks so conventional now," Weinberger said. "It's hard to imagine it was so unconventional then."

On the subject of Soviet leader Mikhail Gorbachev's surprise proposal of a 15-year timetable for banning nuclear weapons, Weinberger was less forthcoming. "I think I'll just stay with the White House statement," he said. "I have a press conference tomorrow. I think I'd better think about that overnight -- if I ever get home," he chuckled as dinner got off to a leisurely late start.

Before dinner, guests like Mayor Marion Barry and wife Effi and Secretary of Education William Bennett mingled among the paintings. Descendants were especially in demand for pictures in front of the pictures done by their ancestors.

"I can't hold my stomach in much longer," cracked a smiling Rep. Jack Kemp (R-N.Y.) standing in front of Renoir's "Danseuse" with Sophie Renoir as photographers snapped away. Sophie Renoir doesn't have to hold her stomach in, because she has none, just the tiniest waist in the world, which last night was sheathed in a crinkly red silk dress and encircled by a leather belt.

"I think, first of all, he'd be proud to be in this exhibit," said Renoir of her great-grandfather. Her parents have Renoirs on their dining-room and living-room walls. "They've given me the bronze bust, 'Coco,' " said Renoir, an actress, of the artist's bust of his youngest son.

Toulgouat has just a small legacy of his great-grandfather's works. "Unfortunately I own only one," he said. "It's my grandmother, Suzanne, with sunflowers." He alluded to some family problems over the painting. "I think we're going to have to sell it . . .," he said and shrugged. "You can't divide a painting."

Meanwhile, everyone connected with the exhibition grinned contentedly, especially AT&T Chief Executive Officer Charles L. Brown. His company underwrote the exhibition of these once-upstarts.

Whose uproar in the art world probably can't be duplicated:

"There's no equivalent to this," said Corcoran Gallery of Art Director Michael Botwinick, "because there was an established style to react against. We don't have that base today."

National Gallery of Art Director J. Carter Brown noted, "I think our whole attitude toward modern artists is much more tolerant." He attributed that in large measure to the Impressionists' break with tradition. "The whole way we view art has shifted because of these eight shows."

And from the man who actually put together this show -- curator Charles Moffett of the Fine Arts Museums of San Francisco (where the show will go): "I've got two years of my life tied up in this. You don't want to fall on your face, especially in front of these people," he said. His friend Franc,oise Cachin, curator of the Muse'e d'Orsay and granddaughter of Paul Signac, had already come up to Moffett last night and delivered her verdict. Moffett recalled, "She said, 'Formidable.' "