Thank God Degas was born in the 19th century (1834). If he were born in, say, 1970, could he have become the masterful and revolutionary painter he was? Not likely. Any serious study of this artist, which should include ³Degas and the Dance² currently at the Philadelphia Museum of Art, shows how fully he reflects his time and culture.

The popular imagination is no longer thrilled and scandalized by new painting the way it was when annual salons were bigger -- in terms of prestige, audience and potential revenue -- than today's ballyhooed bienales. As a young man so drawn to public entertainment that he attended favorite operas or ballets some 30 times, Degas might well have overlooked painting as a vocation in the 20th century.

Second, Degas came to painting late and grew as a painter throughout his life. He was in his 40s when he exhibited with the impressionists. He began painting earlier, of course, and did his first ballet-related subjects, including the delightful Orchestra Musicians, in the late 1860s and early '70s. He was no youth. Today's art world likes its heroes unripe but photogenic.

Third, the city Degas loved and documented -- Paris -- has altered. Gentlemen no longer commune with their fellows in cafés, where the only female patrons are of quite another class. Upper-class men do not patronize sophisticated entertainments like ballets and operas staged exclusively for them.

Don't imagine that Degas was attracted to corruption per se; we see the reverse in the respectable character of numerous dancers whom he chose to befriend, many of whom are identified for the first time in the catalog essays of Degas expert Richard Kendall and dance historian Jill DeVonyar.

Nevertheless, Degas had an eye for artifice and theatricality, evident in his love of backstage and rehearsal pictures. I believe his vision is more ironic than is usually acknowledged. The ingratiating painted smiles on dancers curtsying into the icy glare of gaslights embody glamour and charm, but are they not clearly depicted as masks?

An unusual example of wit and one of the finest paintings in the show, Yellow Dancers (in the Wings), exhibited at the second impressionist exhibition (1876), places a trio of dancers in almost chartreuse tutus in the foreground. They are adjusting their hair and corsages prior to moving on stage, where in the background we see the legs of other members of the corps, visible below the knee, behind a piece of scenery. One might interpret this image as Degas' cynical comment on exactly what men came to the theater to see: women's legs.

But the row of legs also reflects a personal concern with the correct representation of limbs in balletic postures, an obsession repeatedly documented. In his many drawings of dancers, who in Degas' day wore skirts even when taking class, Degas is faced with the problem of showing arms, busts and legs emerging from a froth of fabric. It's a pleasing contrast: filmy swathes of color and firmly contoured gestures of shoulders, necks, calves and ankles.

Just as a dancer, no matter how accomplished, takes class every morning, Degas drew and drew and drew. Ballet positions present challenges in foreshortening. He never flinched from them, but rather sought out these angular, graceful postures. This strict devotion to drawing is the ultimate reason Degas could not have found his métier today. Even among our sadly depleted stock of painters, the abilities of the draftsman and colorist, skills of portraiture, psychological insight and the body in motion, though not without an audience, are not at the forefront. Degas has few rivals in these departments.

Over half of Degas' work is about dancers. He made many wax figures toward the end of his life when he was going blind. Cast in bronze after his death, they reveal his profound grasp of an anatomical shorthand of gesture and rhythm. One must almost restrain oneself from imitating these lively movements. In earlier work, he explores the effects of light and space across a stage or reflected in the mirrors of a rehearsal room, the floor raked as in a Japanese print. He worked in unusual formats that are often surprisingly compact, almost jewel-like. As his sight diminished, the color grew bolder ("orgies of color," he said), but never simplistic.

Complementing the exhibition are numerous contemporaneous items. They include a pair of pink satin toe shoes found with other dancers' paraphernalia in Degas' studio, numerous photographs of famous dancers and three astonishing maquettes of sets for ballets Degas saw and painted.

You may hear some talk that this is just another blockbuster of déjà vu thrills. Don't be cheated by cynicism. "Degas and the Dance" contains works from almost 100 collections. It displays Degas' rigor, revolutionary spirit, musicality and bravura for dancers, balletomanes, painters and the rest of us. We won't see his like again.

Through May 11, Philadelphia Museum of Art, 26th St. and the Parkway, 215-235-7469