Though rich in beloved pictures by Renoir and Monet, Seurat and Pissarro, "The New Painting: Impressionism 1874-1886" -- which goes on view today in the National Gallery's West Building -- is more than just an eye treat. It is, says J. Carter Brown, the gallery's director, "a thinking man's exhibit." Built around an armature of hardheaded detective work, it also feeds the mind.

This scholarly yet scrumptious show demystifies its objects. It asks us to confront them as if for the first time.

It also generates surprises. The conventional contention, expressed in countless lecture rooms, that the Impressionists wholeheartedly relied on painting out-of-doors, flatness, broken brushwork and bright, prismatic colors, is here in part demolished. So is the old belief that their paintings, when still new, all were roundly panned by the critics of the time. The show, conceived by Charles S. Moffett of the Fine Arts Museums of San Francisco, also rearranges our opinions of the masters. For while Degas holds the lead, and young Ce'zanne amazes, Moffett's exhibition has an unexpected star.

He is Gustave Caillebotte (1848-1894). For many years ignored, and still largely unfamiliar to most members of the public, the Caillebotte we meet here is unquestionably a painter of the highest rank.

Neither Moffett nor his colleagues deserve all the credit for Caillebotte's promotion. Nor are they to blame for what might seem omissions -- there are no van Goghs on exhibit, and no Manets. For these 150 paintings -- the Bracquemonds and Le'pines, Piettes and Raffae llis, as well as the Cassatts, the Signacs and Gauguins -- were selected not by scholars, or publishers of post cards, dealers or collectors. All of them were chosen by the Impressionists themselves.

It is that above all else that makes this show important. For it is not just another crowd-attracting, audience-stunning "Treasures of" exhibit. We've had more than enough of those. Nor is it some cranky revisionist display. It is instead an open window to the past.

In the early 1870s, a shifting group of artists, most of them Parisians, began arranging group shows for their peers. Most, but far from all, were committed avant-gardists. Many, but not all, were understandably offended by the academic standards of the French Salons. So they struck out on their own.

At first they chose to call themselves "Artists, Painters, Sculptors, Engravers Inc.," a mouthful that they hoped would help them dodge misleading labels. "I was afraid," wrote Renoir later, "that if we were called the 'Somebodies,' or 'The So-and-Sos,' or even 'The Thirty-Nine,' the critics would immediately start talking of a 'new school.' " Renoir's fears were justified. The artists were referred to as Independents, Radicals, Impressionists and Intransigents (when critics were not damning them as maniacs or lunatics).

Between 1874 and 1886 they organized in Paris eight "Impressionist" exhibitions -- the term, at first rejected, became the one that stuck. Moffett has spent years scanning newspapers and magazines, memoirs, notes and letters trying to determine precisely which paintings were displayed in each of those exhibits. It is from those hard-won lists that he has drawn the objects for his eight-chapter show.

Art labels mislead. Any label broad enough to cover de Kooning's screaming women, Barnett Newman's stripes and Jackson Pollock's drips, "Abstract Expressionism," for instance, has got to stretch a lot. "Impressionism," Moffett's show makes clear, is comparably elastic. The term implies the instant quickly caught. The drawbacks of the term are nowhere more apparent than in a stunning wall of pictures here, all of which were first shown in the Fourth Exhibition of 1879.

They are Degas' "La La at the Cirque Fernando, Paris," a strange but finished picture of a young performer hanging by her teeth; "Laundresses Carrying Linen in Town," an awesomely successful sketch, half-focused and half-summarized, also by Degas; "Sculls," by Caillebotte, a haunting, half-surreal view of pith-helmeted boaters; Federico Zandomeneghi's "Portrait of M. Diego Martelli," an almost academic painting by a now-forgotten painter described, rightly, at the time as "a most transigent Intransigent"; and yet another Degas, "Portraits at the Stock Exchange," a work whose harsh wit and whose faces suggest the paintings of Daumier.

It is not their style, or rather their five styles, that make these works "Impressionist." Their brush strokes do not flicker, their colors do not flare, and few suggest the out-of-doors. What made these pictures "modern" was subject more than style. Signac painted gas tanks. Monet painted steam. An interest in the new, the now, is felt throughout the show. The one thing that these artists shared was an adamant refusal to paint the nymphs and Roman heroes so often seen in the Salons.

The artists called Impressionists agreed on no new style. It was breaking rules that pleased them. Some, Monet for example, liked to work in series. His three railroad station paintings from the Third Exhibition helped to set a fashion for variations-on-a-theme that's still in vogue today. Degas took another tack, at least for a while. In the Third and Fourth Exhibitions, he chose to show pictures of such varied scale, finish and intention that viewers often doubted they were by the same man. In the sixth, he showed a statue, his "Little Fourteen-Year-Old Dancer." His daring and his wit are everywhere apparent. He was a hard man to pin down.

Renoir was more steady. His recent Boston retrospective left the viewer feeling he'd been stuffed with whipped cream. Here, in meatier surroundings, his sweetness is more welcome. Pissarro, the only painter who agreed to show his art in all eight exhibits, was the steadiest of all.

Ce'zanne may have been the most original. His vast formal intelligence, and his refusal to accept the vagaries of fashion, was apparent from the start.

The artists we encounter here had lived through awful times. It is possible to argue that in 1876, with the Franco-Prussian War and the Commune behind them, sudden freedom fueled these artists. We know their pictures well. Yet still it seems a miracle that they all worked at once.

Who knows Caillebotte? Where does he come from? In what school was he trained? No one has been able to tell me. All I know is that Caillebotte is one of the most original painters to have come forward in some time, and I am not afraid I shall compromise myself by predicting he will be famous before long.

The critic Marius Chaumelin made that rash prediction in April 1876. It took longer than he thought.

The Caillebotte we meet here is an idiosyncratic master. Elsewhere in this show, one feels an interest in the fleeting and the incomplete, a hymning of potential. But the Caillebottes are different. A frozen stillness haunts them. Even when he chooses the least exciting subjects -- men refinishing a floor, strollers in the street, a view of Notre Dame or a couple in their parlor -- he somehow makes us feel we are gazing at a dream.

Today he seems a prophet. His "Paris Street: A Rainy Day" predicts the silvery gray light, the stillness and the shimmer of Seurat's "La Grande-Jatte." The small interior that hangs next to it prophesies Vuillard. And his view of Notre Dame recalls a version of the same scene that would be painted decades later by the young Matisse.

His wealth delayed his fame. His father, who'd perfected the spiral metal bedspring, left him lots of cash. While his fellow painters struggled to survive, Caillebotte, a bachelor, an engineer, sought to serve their interests. He did not sell. He bought.

When he died in 1894, he willed to France his 16 canvases by Monet, 7 by Degas, 18 by Pissarro, 8 Renoirs, 9 Sisleys, 4 Manets and 5 Ce'zannes. The nation turned him down. Years of negotiation followed before Renoir, his executor, agreed to reduce the bequest.

No dealers pushed his pictures. Most stayed with his family, and the few that hit the market seemed too strange to be considered typically Impressionist. Because no catalogue was published, few students knew his work. Not until 1964, when the Art Institute of Chicago bought his "Paris Street," did his reputation begin, at last, to rise. His pictures are, in passages, peculiarly imperfect. That boater's foot is awkward, those strollers out of scale, and a few of his interiors seem a bit too blue. But this show makes one thing certain. His fame is now assured.

Conventional accounts of Impressionism's history tend to criticize the critics of the time as blind to the new art. Old Paris newspapers, it's true, provide much grist for the mill. A Renoir nude displayed in the Second Exhibition was described by Albert Wolff as a "mass of decomposing flesh." The critic Emile Cardon thought the Impressionists' "debaucheries . . . nauseating and revolting." Morisot can't draw, Monet is unintelligible, Pissarro's art is laughable -- the gripes go on and on.

But as the present show's vast catalogue makes clear, most of the reviews were on the whole encouraging. Almost all the pictures illustrated are accompanied by critiques written not by scholars, but by critics of the time.

The show, despite its brilliance, is not without its flaws. It would have been yet stronger had it managed to include Seurat's "La Grande-Jatte" (Chicago would not lend), "Impression, Sunrise," the seascape by Monet that gave Impressionism its labels (a painting stolen recently from the Muse'e Marmottan in Paris), Ce'zanne's first great still life (now in Philadelphia) and other crucial works.

The show has been installed in gracious day-lit galleries that, recently completed, are being used for the first time. Those who wander through them will forget the omissions. Time and time again, the masterworks presented -- Degas' "Cotton Exchange at New Orleans," that little Seurat drawing, Renoir's "Luncheon of the Boating Party" from the Phillips, or that Signac from Australia -- take the breath away.

"The New Painting: Impressionism 1874-1886" is sure to be remembered. Its 500-page catalogue -- with its thoughtful, useful essays, its perhaps 1,000 footnotes, and its detailed reproductions of the catalogues for all eight shows -- will become a standard reference work. Even those few crummy paintings rightfully included -- the Astruc, the Desboutin, the Piette, for example -- tell us something useful about the first Impressionists.

The great strength of this show is that it takes us from our own time -- and pushes us toward theirs.

A $750,000 grant from the AT&T corporate advertising budget has helped to pay its bills. The Impressionist exhibit will be seen in San Francisco April 19-July 6. It closes here on April 6.