1910: In Munich, the artist Wassily Kandinsky more or less invents abstraction, by making subjectless paintings that try to capture the energy of music.

1918: In Moscow, Kasimir Malevich pares abstraction down to essences, painting a plain white square on white.

1947: On Long Island, Jackson Pollock lays his oversize canvases on the studio floor, then drips and splatters paint all over them.

1954: In Washington, Morris Louis turns paint into thin stains of color that soak into his huge canvases.

Just a few of many epochal moments in the history of abstract art.

There's one more: In 1969, at the Corcoran Gallery of Art in Washington, 36-year-old Sam Gilliam pulls his canvases off their supports, letting them hang as knotted, stained and spattered "Drapes" across the museum's open spaces.

Now, 36 years later, the Corcoran revisits that moment and others in Gilliam's career. "Sam Gilliam: A Retrospective," the first full-scale survey of the artist's work, premieres at the Washington museum tomorrow, before traveling to several other venues across the country.

This important exhibition at last lets us take the measure of a career that many of us know more by rumor and reputation than at first hand. It lets us answer crucial questions about an artist sometimes said to be Washington's most significant living painter.

Maybe the central question it can answer is why, given the undeniable innovation on view in Gilliam's Drapes, those works somehow feel less consequential than they might. And why, as it turns out, they had fairly little influence on anything that followed.

There's certainly nothing wrong with the look of any first-rate Gilliam. (He has turned out such a vast amount of art that some of it was bound to fail. By showing only 48 works, all from Gilliam's mature career, curator Jonathan Binstock has taken steps to show only the best.)

Gilliam's landmark Drapes fill space as impressively as any monumental sculpture, and they do it in a novel way. There's very little sculpture that has managed to be huge and lyrical at the same time, but Gilliam's use of fabric achieves that combination. His swags of cloth have a domestic intimacy -- just by being swags, and by being cloth -- that keeps them from feeling domineering or bombastic. Their rainbow colors are easy on the eyes, and the occasional splats of paint that smudge their veils of tone give a sense of the painter's studio that they came out of.

Incomprehensibly and unforgivably, the Corcoran has missed this unique opportunity to reinstall the really massive Drapes that filled its open atrium in 1969. But even the more modest, gallery-scaled pieces this show settles for have presence.

Gilliam's more conventional wall-hung canvases, constructions and collages also rarely fail to please. There's an impressive accumulation of paint in his well-known "Black Paintings" from the later 1970s; their layering of tarry black on top of sparkling color makes for a striking marriage of opposites. Even his quite recent "Slats," where deep wells of solid-colored paint cover crisply carpentered wood forms, are awfully good-looking -- and not just in ways that other Gilliams have been. As Binstock points out in his thorough catalogue essay, Gilliam doesn't fall into the trap of many senior artists, who just repeat the works that have won praise.

Weirdly, that variety may point to the crucial problem Gilliam has faced. By changing looks as often as he has, there is a sense that no one option matters all that much.

Earlier abstractionists such as Malevich and Pollock conveyed a sense of a profound, almost absurd commitment to their artistic project. They were arguing, against the odds, for whole new ways of thinking about art and looking at it, and in some sense their pictures stand as markers or metaphors for the courage it took to make them. They and their first boosters billed their art as just about crucial to the fundamental workings of the world; however overblown such claims can seem, their urgency is somehow captured in the art. Abstraction worked as a placeholder for the power of radical innovation in all of life.

By the time Gilliam's pictures came along, however, abstraction had lost that kind of weight. It was pretty much the status quo.

Gilliam's innovative paintings came at the tail end of a tradition rather than in the thick of things. They are the closing parentheses, as it were, on the abstract episode in Western art. They don't point forward to a rich future of further possibilities. They look back on, and are overshadowed by, an impressive history. By 1969, abstract artists weren't just reduced to dotting the i's and crossing the t's of the work that came before; it can feel like they were down to fiddling with the look of other people's dots and crosses.

The obvious, simple problem with Gilliam's art is that it came at the wrong time.

But maybe an obvious problem can also be seen as a subtle virtue. Sometimes, endings can also be beginnings.

It takes a bit of work, but it's possible to see Gilliam as the first of the postmoderns rather than the last of the moderns.

His installations, which sometimes mix draped canvases with raw construction lumber or handcrafted, hand-distressed sawhorses, can feel strangely theatrical. They feel like what a stage designer would come up with for a play set in a heroic modern artist's studio, rather than like the real works of art that would come out of such a studio. That is, they feel like references to modern art, rather than abstract work meant to speak on its own terms, in isolation from the world. You could imagine changing the specific colors or contours in one of those drapes without much harming the overall effect or message that the installation sends. And that's because these works seem to talk about the emptying out of modernism -- its dilution to a bunch of almost interchangeable conceits -- rather than about how much any one modernist detail might signify.

A 1968 piece called "Bow Form Construction" is a single, thickly pleated 27-foot swath of canvas, colorfully stained, attached to the wall at its two ends and sagging gently in the middle. It looks like a picture of an oversize brushstroke. The piece seems to conflate canvas, the classic support of modernist abstraction, and the magical, heroic mark that it's supposed to bear. In the terms of traditional abstract art, that is, it gets things backward, letting canvas do the work of the paint that it's supposed to carry -- and in the process it deflates the grand claims once made for paint strokes applied to canvas. Caricaturists enlarge the single trademark feature of the figures they intend to mock: Dubya's ears; Clinton's bulbous nose. Blow an abstract brushstroke up too big, and it, too, becomes a figure of fun.

There's the same feeling in some of Gilliam's early canvases that come wrapped around stretchers with beveled edges. They give a sense that someone's found a piece of patterned textile, then used it to "decorate" a wall-hung form -- the way you could imagine a hipster designer from the '70s taking tie-dye fabric and using it to wrap around acoustic panels in a campus concert hall. If earlier abstraction believed that its every stroke conveyed an existential state, these new pictures of abstract art show how it can also be just one more feature in our daily life.

There were other, more explicitly conceptual artists making this kind of once-removed abstraction around this time -- the German artist Blinky Palermo wrapped his stretchers in bought yard goods -- and Gilliam's art can seem in step with theirs, whether he intended it that way or not.

According to this "postmodern" reading, Gilliam's attractive abstract art makes a virtue of its decorative surfaces. It denies the grand claims once made for abstraction, or sees them as something past that can never be recovered, and celebrates the simpler business of making fine-looking art.

Gilliam's clotted impastos don't have expressionist angst in them. They're just about how thick an artist can lay down his paint.

His splattered canvases aren't the record of a moment of creative inspiration, the way Pollock's were supposed to be. They are more like homemade art supplies, ready for cutting up and reassembly into well-composed collages.

The slathered colored surfaces of his 1990s works are as close to faux finishes as they are to anything by Franz Kline or Robert Motherwell. And asserting that this is all that abstract art can be is part of what they're all about.

All these decades after Gilliam's first Drapes, which represent the last gasps of truly ambitious abstract art, there isn't even mourning left to do for the movement's once-grand hopes and claims. Gilliam's very latest work, commissioned for the Corcoran's domed rotunda space, is the ultimate example of abstract art as simple visual delight.

Gilliam has hung kite-bright lengths of colored muslin from on high, letting them twist in the smallest draft.

They are a source of pleasure. That's all they want to be.

Sam Gilliam: A Retrospective opens tomorrow at the Corcoran Gallery of Art, 500 17th St. NW, and will run through Jan. 22, 2006. Call 202-639-1700 or visit www.corcoran.org.

Sam Gilliam's "Light Depth," above, and "All Cats Are Gray at Night" are part of the Corcoran's show, the first full-scale survey of the Washington artist's work.

Sam Gilliam, right, and some of his works, clockwise from below: 1973's "Softly Still," canvas draped over a sawhorse, and the vibrantly flowing "Light Depth" from 1969; the hanging muslin of "30,000 Knots," Gilliam's latest work, commissioned for the Corcoran's domed rotunda space; and the cascading colors of "Restore," from 1968.