Vietnam was a long time ago, a whole generation past. The veterans who haunt the Vietnam Memorial in their plaintive fatigues are getting middle-aged. The Marine landing at Danang is more distant than Iwo Jima was for those Marines of 1965. The films and TV tape shot back then -- the gritty chaos of combat, the flaccid grandeur of peace demonstrations -- have the quality of history, some thing abstracted about them; even the color footage seems as if it were in black and white.

Nevertheless, Vietnam doesn't go away. People keep worrying at it with a sort of gruesome tenderness, like a dog gnawing at the cast on a broken leg. It has become an industry and a cause. Any art, journalism or political gesture that arises from anger, bitterness, nostalgia, bewilderment or pain of any kind over Vietnam commands our respect, whether it deserves it or not. It is therapy, therefore it is sacrosanct.

Behind all this lies the same promise that psychotherapy makes about an unhappy childhood -- once Viet nam is remembered properly, it will stop nagging at us. But it doesn't. Since the last of our troops pulled out in 1973 we've had art that has touched the whole country and thanked and remembered its soldiers -- Washington's Vietnam Veterans Memorial designed by Maya Lin, the nearby statue of three servicemen by Frederick Hart, James Webb's novel "Fields of Fire," Michael Herr's journalistic memoir "Dispatches," Billy Joel's song "Goodnight, Saigon" and so on, to mention just a little of it. And it keeps on coming, good and bad.

This year, Hollywood has turned Vietnam into a genre unto itself with movies such as "Platoon," "Full Metal Jacket" and "Hamburger Hill." An ad for television's new dramatic series "Tour of Duty" says that we have to "talk about it," as if we hadn't been doing just that. The books are so many that there are at least two bibliographies listing all the other books on Vietnam. Amlin Gray's play "How I Got That Story" has returned to Washington for another run. The Vietnam Women's Memorial Project is campaigning to put a statue of a nurse near the Vietnam memorial. And who knows what will come next from Sly Stallone, Gloria Emerson, Noam Chomsky, Clint Eastwood, Country Joe McDonald and the journalist-veterans traveling back to Vietnam on their bleak nostalgia trips? In keeping with the spirit of the Vietnam era, when we tended to blur the difference between passion and principle, remembering has become a moral position.

One of the most ambitious attempts to sum up what the word "Vietnam" has come to mean in the American psyche is a three-month program organized by the Washington Project for the Arts, a nonprofit gallery and performance space at 7th and E streets NW. It is called "War and Memory in the Aftermath of Vietnam" and runs through Dec. 19. WPA describes it as a "multidisciplinary program of visual art, commissioned installations, photography, film, video, literature, theater, music and public discussions." Some of it is good, some of it is awful. What is important is that it is utterly conventional -- conventionally shocking, conventionally touching, conventionally moral. It does as good a job as we're apt to get of showing us how we're supposed to feel about Vietnam.

It is by turns heavy-handed, penetrating, nostalgic, ironic, decadent and self-righteous, with occasional unmediated glints of recognition, especially in the snapshots brought home by veterans. These are simple, clumsy pictures of helicopters and rice paddies, of young men holding rifles and squinting into the sun, and they have the power of near-artless fact. But most of the show generates the smog of unreality that hung over the whole era -- the fathomless layering of media, slogans, self-dramatization and illusion.

For example, take the installation called "Hotel Co Hon," meaning "Hotel Wandering Ghosts." It's a big room where everything is black, white or gray: two white French colonial tombs; stone furniture; dozens of black-and-white photographs of Vietnam; blackboards where writing covers writing in layers of chalked quotations: "He would not close his eyes unless there was light nearby ... alive or dead ... and then we were breathing him ..." There are scrolls, a map of Vietnam and a silhouette of the famous photograph of the Saigon police chief blowing out a Viet Cong's brains. There are lots of words, including big black letters misted over by a scrim of white: "LOST IN A ROMAN WILDERNESS OF PAIN."

The artist, a Californian named Richard Turner, was asked recently: Why "Roman"?

"That's the last line from the Doors' song 'The End,' " he said. "That was in 'Apocalypse Now.' "

This layering of imagery goes on and on. In a two-wall exhibit titled "Sorry About That" (the great ironic catch phrase of our troops), Cynthia Carlson has made monotype prints derived from her photographs taken of objects left at the Vietnam memorial. There are three different exhibits of photographs taken there. And a Vietnamese photographer named Hanh Thi Pham offers a picture of an actor in a North Vietnamese uniform who flogs an actor playing a civilian while a print of a black-and-white photograph of Ho Chi Minh lolls in a hammock.

The WPA has put out a 448-page book, and there are another 10,000 or so words on the walls to explain the art. This doesn't count the catalogue, critical brochures, documents, photocopies of magazine articles, five shelves of books and all the words being spoken by narrators, authors and politicians in films and videos played on TV screens scattered throughout this show. Nor does it count three words over the door to the corrosively smug installation by Richard Posner. It is based on the 16 months that Posner spent as a conscientious objector, washing dishes in a hospital. The three words are Arbeit macht frei, meaning "work makes you free." They were also over the gate at Auschwitz. Perhaps Posner can contribute a dishwashing exhibit to the new Holocaust museum.

Words, words, words. Images, images, images.

Vietnam happened in a time when American intellectuals still thought that art could change America and save us from ourselves. The approved tone of that art was one of irony, therapy, alienation and nostalgia. That is the tone of this show.

The ironies range from the snapshot of a soldier posing like a muscle man in the middle of a combat zone to the ham-handed use of the "Battle Hymn of the Republic" in a movie called "Mills of the Gods: Vietnam." Irony ruins a Terry Allen installation called "Tables and Angels," which is cafe' booths inside cages lit with red light bulbs. It has something of the frantic bleakness of the bars on Saigon's Tu Do Street until the sound track of helicopter noise (which sounds more like a railroad train) shifts to a harmonium playing a wheezy "My Country 'Tis of Thee," and then it just seems sophomoric. In one booth there's an empty bottle of vitamins with a napkin reading: "The illness has spread in and out of the immune system ... personal and collective ... we have no vitamins to heal the wounds ... we have expression only ... and thank God(ess) for that." There it is: Vietnam, not to mention all of American life, as a disease, with the only cure being expressing oneself.

The alienation shows up in, say, Lloyd Wolf's photographs of people at the Vietnam memorial. In the tradition of Diane Arbus or Lee Friedlander, he shows us frightened, puzzled, freakish people. Alienation even appears in a backhanded sort of way in the dye-transfer color photographs by Larry Burrows, a Life magazine photographer who found Yeats' "terrible beauty" in Vietnam, as in a stunning photograph of soldiers carrying the wounded through windblown grass. But that beauty puts you at one remove from the combat he portrays. It makes Vietnam static and final, kind of like the America you used to picture when you finished reading an issue of Life in the 1950s. More immediate, by comparison, are those veterans' snapshots, as in Nancy Floyd's memorial to her brother James M. Floyd, or the photographs taken by an ABC television cameraman named Don North. He lacks Burrows' finesse, but that lack puts him closer to his subjects -- a picture of a man giving mouth-to-mouth resuscitation to a wounded comrade is enough to make you cry.

The Vietnam era was a decadent one, and decadence prompts nostalgia -- the Lost Generation in the Paris of the '20s, the Beat Generation of the '50s, the Weimar Republic, turn-of-the-century Vienna.

In America back then, the decadence on both sides of the war was more than the violence, intellectual arrogance, situation ethics, self-righteous hating and cookie-cutter "love" of the kind that was always trying to sell something. (Remember all the horrible smiling -- by Lyndon Johnson when he wound up his speeches, by protesters when they inserted flowers into National Guard gun barrels?) What was decadent was the belief that the abandonment of law and custom, along with embracing outrage and cultural anarchy, would lead us to some higher good.

Everybody marched to different drummers, and all the drummers were taking nonstop apocalyptic solos. We could hardly wait for the world to end: the college kids reciting Yeats' "A Second Coming"; the John Birchers waiting for the Commies to land on Cape Cod; the marijuana Buddhists keeping their bathtubs full of drinking water in case the revolution happened that very night; and the men in Vietnam who played so many variations on the romance of irony and despair: "It don't mean a thing"; "Better him than me"; "No more boom-boom for that mama-san." There was a hellish glamor to it all, not to mention the glow of moral certainty, and a sound track courtesy of the golden age of rock 'n' roll. No wonder people can't let it go.

This nostalgia and romance may account for the heaviness of so much Vietnam art, both good and bad -- a sodden, drugged quality. Think of "Dispatches," or movies such as "The Deer Hunter" or "Apocalypse Now." Look at an absolutely silly movie in the WPA program called "Aspects of a Certain History," in which, among other things, the camera gives us the outside of an American barn for minutes on end while Vietnamese words appear on the screen, untranslated. It's like the worst possible combination of a Noh play and a slide show from the Dairy Council. Look at the 16 skull-sculptures on sticks in the powerful Joe Shannon installation in the basement at WPA. (They recall "Apocalypse Now," which took them from Joseph Conrad's "Heart of Darkness.") It is called "Leroy's Tour." There are slides from Vietnam, there are slides of a black man painted with spots dancing around naked. There's a sound track on which a woman sings, in the kind of music that gets played when the credits come up after a long, exhausting weeper of a movie: "There is sensation ... somewhere within the nation ..."

There was indeed. It was the Age of Feelings, a sort of secular Sacred Heart movement that dwelled on ecstasy and suffering, and Shannon captures it.

What has been left out of the show is just as important as what's in it. These are the conventional omissions.

There is little hint of the bravery, loyalty and skill with which American troops fought a pathologically warlike regime -- Vietnam today, 15 years after our troops left, has a larger standing land army than we do.

The show dwells on our defeat but largely ignores the communists' victory. This is perhaps because they failed utterly to live up to their American admirers' pipe dreams of democracy and the New Man. Also, noting a victory would go against the piety that in war there are no victors. Tell this to the boat people who fled Vietnam in 1975. The only hints on WPA's walls of communist cruelty and corruption come from quilts by Hmong tribesmen and the photographs by Hanh Thi Pham.

There's little in this show about the satisfactions and pleasures of war. This would be heresy. But pleasures there are in slaughter, which is one reason wars get fought, and a very big reason they get won. One film from 1968, Emile de Antonio's "In the Year of the Pig," shows Col. George Patton III talking about attending a memorial service the night before. He says his soldiers were "determined" and "reverent," and then his face stretches out in a ghastly grin as he calls them "a bloody good bunch of killers." Is it the British slang that's troubling? Is it the grin? A Canadian documentary, "Mills of the Gods: Vietnam," shows an American pilot strafing and bombing. Moments afterward, in the cockpit of his A1A Skyraider, he says: "That's great fun. I really like to do that. We really hosed 'em down." In the air-conditioned hush of a movie theater (the films are being screened at the American Film Institute and other theaters) these statements are grotesque. There's no way they couldn't be, wrenched out of a context as impossible to imagine as combat.

The Department of Defense didn't do any better with a propaganda film from 1965 called "Why Vietnam?" It provokes the same suspicion that somebody is blowing smoke at somebody; it even contains some of the same footage as the antiwar films, such as shots of the overrunning of the French at Dien Bien Phu in 1954, which of course were staged for the cameras by the communists after their victory. WPA says "Why Vietnam?" was shown to troops embarking for Vietnam. They must have really hit the beaches running after watching Secretary of State Dean Rusk discuss the finer points of negotiations.

There was so much pathetic hooey from leaders and intellectuals on all sides during Vietnam. Consider Lyndon Johnson mouthing the platitudes of internationalism and asking our soldiers to fight for peace, not victories, which is a little like asking football players to play a Super Bowl for the exercise. Consider a left-wing film called "The People's War," which shows the North Vietnamese people planting rice, sawing wood, building boats and generally working like the sort of cheery beavers that only the young and/or educated can believe in, people who themselves have never done manual labor except as part of some politically correct getaway, like flying down to Cuba to help cut sugar cane. It also has a North Vietnamese saying: "We want to remember everything, not only our suffering but our hatred and our victories." Most Americans see no virtue in remembering hatred, but it would be nice to remember the victories along with our suffering. We fought well. We should remember that.

Film had a lot more power to persuade back then, when we were still fascinated with the medium. Now, it seems clumsier. A look at half a dozen or so of the scores of films in the WPA program demonstrates that it isn't the images that have the power, it's the sound track. "The People's War" begins with shots taken from a vehicle moving quickly down a narrow road. Add the sound of explosions, and the film evokes the horrors of the bombing of North Vietnam. Take the explosions away and all you've got is a travelogue.

The WPA's book is called "Unwinding the Vietnam War." It's an anthology published by the Real Comet Press in Seattle. What good writing there is gets asphyxiated by the whining and cliche's. There's poetry that you could retype as prose and no one would know the difference. There's the claim that a deserter who died of a drug overdose was as much a "victim" of "the '60s and that war as anybody."

Here is the therapeutic ethos: "A larger national healing depends first upon hearing the anger and pain of the veterans." Here is the dawning of the Age of Aquarius, in the announcement that this book supports "the shift from a mechanistic to a holistic conception of the world." And don't forget, folks, war is bad for your sex life, too: "The Soldier is virtually incapacitated when he meets women. We reduced our sexuality to an organ requiring periodic discharge. But ... women do not want to be targets in some sexual shooting range."

It wasn't much of a war, but it was the only war we had, as the staff sergeants used to say. Now the veterans of the antiwar movement seem to be saying the same thing. Once it looked as if we'd forget all about it, as we forgot about Korea. Now we can't stop remembering. Maybe it's all culminating this year, maybe Americans will feel either satisfied or fed up and Vietnam will be left in peace. Maybe it will turn into bad box office, and Hollywood will lose interest. Maybe we'll learn to make art about it without all the conspicuous irony, leaden sanctimony and chronic victimhood -- would it even be possible to do comedies that could be to Vietnam what "Mr. Roberts" or "Catch-22" were to World War II? In any case, it's hard to imagine that Vietnam won't be good for years more fellowships, foundation funding and graduate design projects. So far it has been like a tapestry that some national Penelope keeps weaving every day and unweaving every night while she waits for her Ulysses to come home a hero. Will she recognize him when he does? Will she be glad?