Among the first, but not the last, to tire of the impressionists was the French painter Paul Gauguin, who'd once been one himself.

In 1896, briefly back home on a visit from the palm-tree-shaded isles of the far-away South Seas, Gauguin made a prophecy.

"The Impressionists," he wrote, "are the official [painters] of tomorrow, terrible in a different way from the official ones of yesterday."

Turns out he was right.

The works of the impressionists--those bright untroubled pictures of ladies in big hats, and weekends in the country and flickerings of light--were once considered dangerously radical. Not anymore. Now no art is safer. They used to smell distinctly of poverty in Paris. Now they smell of cash.

Million-dollar Renoirs in elaborate gold frames are a staple of the market. The auction rooms depend on them. Very wealthy people hang them in their houses. For the builders of motels, impressionistic pictures, diluted into kitsch, are standard decorations. For the busy manufacturers of calendars and postcards and coffee-table books, School of Paris paintings are salable commodities. For public art museums they're a guarantee of gate.

"Faces of Impressionism: Portraits From American Collections" at the Baltimore Museum of Art may have a higher purpose, but I'm not sure what it is.

In this sprawly and disjointed show, impressionist portraits--and pre-impressionist portraits, and post-impressionist portraits and paintings that aren't noticeably impressionist at all--are all mixed up together. Some of them are excellent. Some are worse than mediocre. When it comes to luring visitors that doesn't seem to matter. When I visited the other day the galleries were full.

Grab-bag exhibitions, which bore such foggy titles as "Masterpieces of Impressionism," used to be enough to pull in curious crowds. Now you need a hook. In recent years, in consequence, important art museums have been cutting up the subject into thinner and thinner slices.

Post-impressionism was the theme of a fine show at the National Gallery of Art 19 years ago. Pre-impressionism was the subject of "Origins of Impressionism" at the Metropolitan Museum of Art in 1995. "The New Painting: Impressionism 1874-1886," a scholarly reprise of the movement's first eight exhibitions, appeared at the National Gallery in 1986. Then the slices grew thinner--especially at the Phillips Collection, which offered "Impressionists on the Seine" in 1996-97 and "Impressionists in Winter" in 1998-99. All of these exhibitions were more carefully considered than the one that's now on view.

"Impressionism" is, of course, a relatively blurry word. Any term that's loose enough to wrap itself around the very different pictures of Edgar Degas, Paul Cezanne and Berthe Morisot has got to be elastic. Still, the label's useful. When one hears the word "impressionism" two thoughts come to mind.

One's a thought of surface. Rejecting the high polish of the official Salon art, the impressionists, in general, embraced the formless and the sketchy. They seldom smoothed their surfaces. They liked striking, sun-bright colors more than they did dull ones. Their pictures seem to flicker, and their brushes seem to fly. Something new in painting, a sense of newfound speed--of quick glimpsing and quick painting--energized their art.

They were modern in their subjects, too. Instead of painting noblemen performing noble deeds, or goddesses, or nymphs, the impressionists preferred contemporary sights. Their central theme was modern life--its cafes and its pickup joints, its popular performers, its bathers and ballets, strollers in the streets. Most impressionists were city folk. Few of them were rich enough to own chateaux in the countryside. But newly busy railroads sped them deep into the suburbs--and they gladly put the trains, and their weekends out of town, into their works of art.

Their portraits, too, in general, were intentionally contemporary. Distrustful of the pompous, they much preferred the casual, unassertive pose. They rarely portrayed rulers, but often painted pictures of their fellow artists, and families, and friends. People in their portraits seldom do heroic things. Often they just sit there in characteristic places--smoking their cigars, or sunning in their gardens, or flipping through the pages of a newspaper or book.

Intimacy, frankness, affection and goodwill are touchstones of this art.

But these are generalities, and most are contradicted by canvases selected for the Baltimore display.

Ignace-Henri-Jean-Theodore Fantin-Latour was, at least in style, scarcely an impressionist, and there's not much that is casual (except perhaps a memory of strolling to the studio) in his famous formal portrait of the great Edouard Manet from the Art Institute of Chicago. Manet got all dressed up to have his portrait painted. He wears a silk top hat, his gloves are of kid leather, his watch fob is of gold.

Not much more "impressionist" is Jean-Frederic Bazille's "African Woman With Peonies" (1870), a painting that was given by the late Paul Mellon to the National Gallery of Art. The woman in the picture is not a contemporary Parisienne, but a hired turbaned model whose dark skin lends a tone of conventional Orientalism to this good, but conventional, studio piece. Even less "impressionist" are two Mary Cassatt portraits. One's a half-completed likeness of the painter's "mulatto servant girl"; the other is a study of an anonymous Italian model depicted by Cassatt in a faux-16th-century manner.

Looking at such canvases, one cannot help but wonder: Why are these things here?

The same question occurs when one's confronted with the pictures by Gustave Courbet and Thomas Couture that begin the exhibition. The Courbet--"Portrait of Clement Laurier" (1855), from the Milwaukee Art Museum--is a typically romantic image: Laurier wears a big black cape; behind him is a stormy sky. The Couture--"A Cuirasser" (1856-58), from Omaha, Neb.--is equally romantic, and equally unlikely: What's a sitter in gilded armor doing in an impressionist display?

Both painters, explains Doreen Bolger, the museum's director, in her preface to the catalogue, are "pivotal precursors of the movement." But what of all the other precursors omitted--what of Delacroix and Daumier and the Barbizon School painters, what of Carolus-Duran and Degas' hero, Ingres? Tattered at its start, the Baltimore exhibit is as tattered at its end.

The eighth impressionist exhibition was held in 1886. Gauguin's "Upaupa Schneklud," from the museum's own collection, was painted eight years later. The cellist who's portrayed, amid tropical foliage, wears a Superman-blue suit and plays an orange instrument. If you're going to end an impressionist show with post-impressionism, one work is insufficient. It's a fine canvas, but its presence here confuses. If you're going to show the post-impressionists, why not include Vincent van Gogh, or Vuillard or Bonnard? Again one stops to ask oneself: Why is this thing here?

But these are grumbles. If you're going to pay the $6 admission fee to "Faces of Impressionism" you might as well enjoy yourself and go for its best pictures. Its works by Degas are exceptional. Of the eight on display the one from Boston--of the painter's younger sister and her Italian husband--is the most intense. The four Cezannes are even stronger. Two depict his wife, Hortense. In "Madame Cezanne in Blue" (1888-90), from the Museum of Fine Arts, Houston, a kind of fright mask, unexplained, hovers by her head--a head that she tilts gently in a gesture of despair in "Portrait of Madame Cezanne with Loosened Hair" (1890-92) from the Philadelphia Museum of Art. In their wordless way these two monumental pictures tell you more about that marriage than you really want to know.

The Manets are as fine. Manet and Cezanne are, at least for me, the period's mightiest painters. Even at his weakest--and the Baltimore Museum's "Lady with a Bonnet" (1881) is nothing to write home about--Manet is worth seeing. His intelligence is huge. His 17-inch-high "Portrait of Victorine Meurent" from the Boston Museum of Fine Arts--she's the model who appears in his "Olympia," and in his "Luncheon on the Grass"--has a candor that still startles, and may be the most memorable canvas on display.

Late 19th-century Paris was conflicted about portraiture. Photography already had made the painter's role as recorder of the face a little problematic. The newly prosperous middle classes, remembering perhaps the stylish accouterments of the aristocracy, were busily commissioning portraits of their families, which most painters had to paint if they wanted to survive. "The only people still buying paintings," complained the novelist Emile Zola in 1868, "are those who want portraits of themselves."

The artist's plight in those days was anything but easy. That may partially explain the mood of jittery uncertainty that prevails in this show.

It was curated by Sona Johnston. Its Baltimore display is supported by Deutsche Bank and Deutsche Banc Alex. Brown. "Faces of Impressionism" will travel to Houston and to Cleveland after closing Jan. 30.