FASHIONED from butterflies' wings. Alive with light. Dazzling like bright afternoons. "The New Painting: Impressionism 1874-1886" is casting its glow on the West Building of the National Gallery.

Ridiculed a hundred years ago, that French avant-garde movement we call Impressionism is now a resounding favorite, and a confirmation of the expression, pretty as a picture.

The works in the show -- the most exciting one here since the American paintings visited the Corcoran -- were actually chosen for exhibition by the artists themselves. As a counterthrust to academic, government-sanctioned Salon shows, the artists held eight, non-juried, independent shows in Paris between 1874 and 1886. And so the National Gallery's exhibition, organized with the Fine Arts Museums of San Francisco, breaks down into eight parts, with 150 representative works from those original eight shows.

"The New Painting" has two faces. One, a lovely visage -- soft, bright and beautiful limnings of life. The other, an earthier outline -- of artists' egos and defections, the battles over who would exhibit and who wouldn't be caught dead with a pointillist or a mediocre realist.

Topping it off, the critics' rampant venom, remembered better than some of the paintings themselves:

On Degas: "His laundresses will never get my business."

On Morisot: "Her feminine grace lives amid the excesses of a twisted mind."

On Caillebotte: "Everything he does is blue."

On Cezanne's "Head of a Man": "Deliberately odd."

On Monet's "The Turkeys": "He doesn't care to turn his stutterings into speech."

On Renoir's study of a female nude: "Depressing -- its flesh has the purplish tones of meat gone rank."

But there were a few critics who sensed something more than daring was afoot -- a revolution. Said Ernest Chesneau, in a review for "Paris-Journal," "What a bugle call for those who listen carefully, how it resounds far into the future."

Impressionism was a new way of seeing things. It was more than Monet's plein-air painting -- outdoors, where the best lighting brought out the truest colors, where the breeze ruffled the skirts of his wife, standing on a hill and holding a parasol. It was his assertion that there was no one best angle for a subject -- and this was underscored by his seven different views of "La Gare Saint- Lazare" (four views are in this show), the train fulminating in the station, filling it with white plumes.

It was more than Degas' modern-life subjects, the portrait of his family members loosely disguised as office workers, or the dangling Miss La-La, the acrobat who hangs by her teeth. It was how he illumined her in light from below and placed her at a dizzying height. Or, in a painting of a roomful of ballerinas, how he showed us a few from the knees down, scurrying down a spiral staircase to join the others in preparation for the dance.

In pointillist perfection, Camille Pissarro's "Apple Picking" expresses more than what is there; with a barn's shadow cast on the field, it shows the effect of what is not there.

Impressionism was more than Caillebotte's choice of a very ordinary subject, "The Floor- Scrapers." It was his vantage point, looking at the workmen from above. (For some reason, one tends to overlook Caillebotte -- but his 15 works here clearly show him among the frontrunners, giving us another body of work to love. In the first gallery, the National has hung a single painting -- one by Caillebotte, which puts us on notice that he is one to watch. By the end of the show, one agrees with Emile Zola's assessment, numbering him "among the boldest of the group.")

Manet said it first, thumbing his nose at the establishment by reworking a classical subject of gods and nymphs into a contemporary semi- naked lunch, two nude women and two fellow artists in "Le D,ejeuner sur l'herbe." Not only irreverent but, why, he paints a picture plane astoundingly flat! But Manet, the putative leader of the Impressionist movement, is conspicuous in this show by his absence. He would have it no other way. Continuing to submit his work to the Salons, he refused to participate in the renegade Impressionist shows, most likely because there were no juries to keep out the second-rate riff-raff.

There may be a few of those strays in the current show. And a few surprises, as well. I rather liked Jean Francoise Raffaelli, whose "Les Declass,es," two skinny down-and-outers, share a carafe of absinthe at their own personal outdoor cafe.

Raffaelli doesn't fall under the Impressionist label, but that's part of the wonder of this show: It gives a wider view of what the painting scene was then. Says Charles Moffett of the Fine Arts Museums of San Francisco, and coordinator of this show, Impressionism "was only a part, a very major part, of avant-garde painting in the '70s and '80s."

But, he says, "I don't expect people to stop using the word Impressionism."

Any more than one can stop thinking of "The Seine at Argenteuil," Monet's bright infusion of sunlight over the cool-toned river, and the dappled path inviting us to stroll.

THE NEW PAINTING: IMPRESSIONISM 1874-1886 -- In the West Building of the National Gallery of Art through April 6. You can secure free advance passes to the show from TicketCenter (in all Hecht's stores), or you can have them mailed to you by calling TicketCenter, 432-0200, any time between 10 a.m. and 10 p.m., seven days a week. For Maryland, Virginia, Delaware, Pennsylvania, New Jersey and New York City, a toll-free number is available: 800/448-9009.