"Five or six lunatics -- among them a woman" is how the haughty critic for Le Figaro described the Impressionists exhibiting at Durand-Ruel's in Paris in 1876. Today we're tickled by his silliness. It is easy now to smile at his savaging of Degas and Pissarro, Renoir and Monet. But our contemporary laughter has a hollow ring. For a subtler dismissiveness, a lingering condescension, harder to eradicate, still dims our comprehension of the extraordinary woman at the center of that show.

Her name was Berthe Morisot. As much as any man, she gave birth to the new painting. She was unswerving in her loyalty to the Parisian avant-garde. She moved her brush as freely as any artist of her day. And it is possible to argue that she taught, by her example, masters as diverse as Monet, Manet, Matisse, Vuillard and Bonnard. Yet while Renoir's is a household name, Morisot's achievement -- she was surely Renoir's peer -- is still misunderstood. She has never had her due. Most textbooks treat her lightly. The market does the same. She died at 54 in 1895, yet never, until now, has Morisot been honored with a grand museum show.

"Berthe Morisot: Impressionist," which goes on view this morning in the National Gallery's West Building, is slightly repetitious and not overwhelming but it literally dazzles. Her pictures have about them something not quite graspable, a fluidity, a shimmer, a shining white-on-whiteness. They're like reveries in sunlight. Thirty crucial years in the story of French painting -- 1864 to 1894 -- are covered by the hundred pictures on display. Their mix of calm and quickness, their modesty of scale -- and the parasols and veils and long skirts of their models -- bind them firmly to their own day. But they are also unavoidably nailed into ours.

In 1987 (the year that saw the opening of the National Museum of Women in the Arts), one insistent question -- How does one explain the comparative neglect of a painter so important? -- runs like shining steel through the gauzy, opalescent quiet of her art.

Curator Charles F. Stuckey, the imaginative young scholar who arranged the exhibition, offers many answers. "What we now call sexist attitudes" is, he writes, "chief among them."

Stuckey, 42, knows far more about the spirit of our own age than most scholars in his field. He has immersed himself as deeply in the contemporary art of Andy Warhol, Scott Burton and Mel Bochner as he has in the paintings of Toulouse-Lautrec and Manet. He has worked in great museums (the Art Institute, the Met), has taught at universities, holds a doctorate from Penn, but still describes himself as "an anti-academic." He worked for 10 years as a critic for Art in America, a national art magazine, mostly writing on the new. Stuckey is preparing the Gauguin retrospective that will open here next year, but he no longer is employed as the National Gallery's curator of 19th-century painting. He has taken a new job. Last week he became curator of 20th-century art at the Art Institute of Chicago.

Sexism is a loaded word, a term with implications. It might lead one to suspect that Morisot was shunned by the macho, revolutionary male painters of her day, that the Salons refused her pictures, that the market would not touch them, that the mores of the time kept her at the fringes of both the art establishment and the Parisian avant-garde. But none of this is true.

On March 2, 1896, the first anniversary of her death, more than 400 of her pictures were gathered at her gallery for a memorial retrospective. Four of her old friends were there to supervise the hanging. They were the painters Edgar Degas (1834-1917), Claude Monet (1840-1926), Pierre Auguste Renoir (1841-1919) and the poet Ste'phane Mallarme' (1842-1898), who had also written the preface to the catalogue. "No exhibition in the history of art," writes Stuckey, "has ever had a more distinguished installation committee."

Morisot was just 14 when, in 1856, accompanied by her sister, Edma, she began to study painting. "Work," she would write later, "is the sole purpose of my existence." The depth of her commitment was apparent from the start. "Given your daughters' natural gifts," her teacher wrote her mother, "it will not be pretty drawing-room talents that my instruction will achieve; they will become painters. Are you fully aware of what that means? It will be revolutionary -- I would almost say catastrophic -- in your high bourgeois milieu."

Some of France's finest painters -- Henri Fantin-Latour (1836-1904) and the much older Camille Corot (1796-1875) -- soon were dining regularly at her family's plush home. While it is certain female painters often found their sex a drawback in the art world of the time (the Ecole des Beaux-Arts was completely closed to women until 1897), Morisot's femininity provided advantages as well. She was first of all a beauty, self-possessed, intelligent, pale-skinned, dark-eyed. The great Edouard Manet portrayed her perhaps a dozen times ("Repose" of 1870, one of his most important portraits, lent for the occasion, hangs just outside the show). She was born into a class one might call bourgeois patrician. Many were her suitors (the artist Pierre Puvis de Chavannes, one of France's best-known painters, was for years her favorite). She was educated, elegant, tough, sophisticated and, by any measure, highly eligible, too.

The landowner she married in December 1874 was connected to the wealthy and to the world of art as well. His name was Euge`ne Manet. Himself something of a painter, and a novelist as well, Euge`ne was the brother of the great Edouard Manet.

Though Fantin and Manet and other artists by the thousands had had their works rejected by the strict conservatives who ruled the French Salons, some of Morisot's submissions -- perhaps in part because of her family's connections -- were selected for inclusion every time she entered. Degas and Pissarro and the other revolutionary painters known as the Impressionists who began exhibiting together in 1874 wholeheartedly accepted Morisot as well.

So, too, did the market, at least what market then existed for the radical new art.

It is difficult today to imagine the ferocities that then colored the disputes between the champions and the foes of revolutionary painting. In 1875, with Renoir, Sisley and Monet, Morisot helped organize an auction of recently made works by daring living artists. Vituperation filled the newspapers. "The impression which the impressionists create," wrote the critic for Le Figaro (his name was Albert Wolff), "is that of a cat walking on the keyboard of a piano or of a monkey who might have got hold of a box of paints." Catcalls filled the hall. When one detractor referred to Morisot as a "whore," Pissarro punched him in the face. Police were summoned to the sales room to quell the resulting brawl. Still some pictures sold. Those by Morisot fetched the highest prices.

William Merritt Chase -- the American impressionist whose small, delightful show of Long Island landscapes, "Summers at Shinnecock: 1891-1902," goes on view this morning in the Gallery's East Building -- was a Morisot collector. So were Mary Cassatt, Degas, Monet and Renoir. One cannot scan the pages of Stuckey's exceptional catalogue without being struck by the almost unbelievable circle of her friends.

Berthe and Euge`ne had a single child, Julie. When Berthe died in 1895 (the death certificate described her as "without any profession") Mallarme' and Renoir became Julie's guardians. Stuckey writes: "Only three years later, her guardian Mallarme' died. Degas, who not without regret had never married, played matchmaker to bring Julie together with Ernest Rouart, one of the sons of Henri Rouart, his wealthy schoolmate who had exhibited with the Impressionists from the start and formed an unsurpassed collection of 19th century French art. Degas's efforts led to a double wedding: {Julie's cousin} Jeanne Gobillard married the poet Paul Vale'ry at the same ceremony."

The question still remains. Given her life's story, the beauties of her pictures and the distinctions of her circle, how is it that Morisot is still popularly regarded, if thought about at all, as relatively insignificant?

That she was a woman is not the only explanation. The continuing prosperity of the Manet-Rouart family is to some degree responsible.

And a good part of the answer is found within her art.

The viewer who looks closely at passages of her paintings -- at the brown and scumbled parapet of "The Harbor at Lorient" (1869), at the gauzy cover of "The Cradle" (1872), at the horse cart in the background of "Reading" (1873) or at the swirling background of the 1879 "Woman at her Toilette" (an oil that was bought by William Merritt Chase) -- has to be astonished by the freedom he sees.

No wonder Albert Wolff thought such works unfinished. The horse that pulls that cart is a single daub of white, the background of the "Toilette" is like a windblown sea of whites and grays. Brushwork of such wildness would not be seen again until the postwar Action Painters would make such gestural daring a hallmark of their art.

Degas also understood the beauty of such free, spontaneous marking. But Degas, unlike Morisot, was a draftsman of wonderful incisiveness. The sharpness of his eye, the precision of his drawing, somehow kept his wildness corralled. Morisot's runs free. Her brush strokes, while they summon up the modest images they show us, have a strange untethered liveliness, a life that is their own. Not until Ce'zanne achieved his greatest freedom would surfaces so active be permitted to perform out there on the canvas, right before our eyes.

Yet the subjects her strokes conjure are, at least to modern eyes, comparatively conventional. Morisot does not depict cancan dancers, nightclub stars, absinthe-besotted drunks, railroad stations, brothels. She shows us children in a garden, children by a pond or a woman at her sewing. Growing up in Paris, she painted with her sisters. As soon as she was married, she painted with her husband. Little Julie joined them as soon as she was old enough. The three painted one another or the fruit trees in the garden they were looking at together. In almost every picture here Morisot presents us with calm domestic comforts, placid scenes of daily life.

Her style is subversive. Her subjects are the opposite. It seems to me some portion of the recognition due her has been lost within that chasm yawning at the center of her cautious, daring art.

Another sort of gap -- the one that seems to open between private musing and hardheaded observation -- exists within her painting. Her subjects often turn away or gaze into the distance, lost in their own thoughts. Often in this show, as Stuckey observes rightly, we seem to be positioned at the shoulder of the painter, watching while she works. These are pictures about looking. The people Morisot portrays, Julie in particular, often seem to gaze at something they alone can see, or something out of sight.

Certain well-known painters stab us with their pictures. Morisot holds back. If her pictures seem unpolished, it is in part because she always had the courage to resist the extra mark. Look, for instance, at the corners of "Euge`ne Manet and His Daughter in the Garden" (1883). The upper left is almost blank, the lower left a few green scribbles. She knew exactly when to stop.

Her pictures unfold slowly. They rarely shock or startle. Some part of the blame for the painter's long neglect has to be apportioned to the peculiar, layered quiet of her art.

One reason art textbooks give her such short shrift is that her paintings lose their life when seen in reproduction. Their colors are too closely tuned. And to see, to truly see them, the observer must be able to view them from a distance, then scrutinize them closely, and then retreat again.

Her pictures would be better known were there more of them about. Washington is lucky. A few collectors who gave paintings to the gallery -- Chester Dale, John Hay Whitney and Paul and Ailsa Mellon -- have searched the market for her pictures. (Together with her family, these collectors have provided a good fifth of this show.) But in many fine museums her works are rarely shown. She didn't really have to sell them; she always had enough to live on. And after her death, Julie's family -- like that of the painter Gustave Caillebote (1848-1894), another first-rate artist rich enough to keep his pictures from the market -- had sufficient wealth to keep their finest Morisots at home.

Morisot is sometimes denigrated wrongly as a painter of the second rank, a sort of gifted amateur, a somewhat imitative painter and a mascot of the masters. But Stuckey, in his catalogue, makes convincing claims for her unsung contributions to the growth of the new art.

Consider, for example, the once radical idea of painting works in series. The long and complex history of 20th-century paintings is near inconceivable without it. The credit for that move is conventionally attributed to Degas, with his many paintings of the ballet, or Monet, with his sequences of train stations and haystacks. But there is evidence to indicate that Morisot got there first.

Stuckey calls attention to the series of five seascapes, all seen from the same vantage point, that Morisot produced while visiting the Isle of Wight in 1875. She exhibited them together. Two are in the show. Their shorthand is amazing. When she made these pictures, Stuckey writes, "none of her Impressionist colleagues had yet worked in such an experimental vein."

Morisot is often seen as a sort of creature of the great Manet, but the learning went both ways. The image of the little girl with her back turned to the observer -- she is looking with a child's innocence and wonder at the same scene that we see -- is crucial to Manet's grand "Gare Saint-Lazare" in the gallery's collection. That painting bears the date 1872-73. Morisot had used that same device half a dozen times at least a year before.

Even Monet's haystacks have precedents in Morisot. There is a portrait of a haystack here that Morisot completed in 1883, at least a year before Monet turned to the same subject.

Matisse in Nice spent many years painting just one scene, a model in a room. Vuillard, too, was quite content to paint the daily life he saw in his mother's small apartment. Morisot, before them, turned her daily life, her husband and her daughter and the places where they lived, into a whole world.

"She would take up her brush," wrote Vale'ry, "leave it aside, and take it up again, in the same way a thought will come to us, vanish and return. It is this which gives her works the very particular charm of a close and almost indisoluable relationship between the artist's ideals and the intimate details of her life."

Morisot throughout her life was a woman of complexity. No wonder masters in such numbers admired her so greatly. One sees why in her art. She was adamant yet subtle, challenging yet comforting, fiercely loyal to her friends and just as fiercely independent, sheltered in her world yet exceptionally free.

"Whenever she works," he mother wrote, "she has an anxious, unhappy, almost fierce look." Morisot, who compared the act of painting to being "engaged in a pitched battle," was often overcome by doubts, and yet she persevered. This show will earn her champions. History will never rank her quite as high as it does those three chief masters of her circle, Degas, Manet and Ce'zanne. But among the rest of the Impressionists she did not have many peers. She made liberated art.

The gallery's exhibit was conceived as a way of celebrating the sesquicentennial of Mount Holyoke College. Stuckey says he would not have been able to put it together had it not been for the contributions of William P. Scott, a Pennsylvania painter who early fell in love with the art of Berthe Morisot and, seeking out her family, became their trusted friend when he was just 15. Scott produced a useful essay for the catalogue. The Morisot exhibit will travel to the Kimbell in Fort Worth, and then to Mount Holyoke, after closing at the National Gallery on Nov. 29.