Like Hollywood, Hell, ancient Rome, Shangri-La, the Old West or Atlantis, the Soviet Union, for most of us, is something we invent. It's a concoction, a bad dream, a straw man, an explanatory principle, a utopia, a bit of wishful thinking or a taste to be acquired, for good or ill. Just now, thanks to charming Soviet leader Mikhail Gorbachev, his nicely dressed wife Raisa, and his glasnost (openness) and perestroika (restructuring), it is the flavor of the month.

Hip boutiques are selling Lenin pins and hammer-and-sickle T-shirts. We're giving Gorbachev approval ratings higher than those for all the Democratic candidates except Jesse Jackson. The Washington Blade, a gay newspaper, ran an ad for a Mrs. Gorbachev look-alike contest. Russian language studies in American colleges and universities are up almost 12 percent since 1983. During a fashion show in October, actress Colleen Dewhurst watched Soviet couturier Viyacheslav Zaitsev twirling before the crowd in his emerald green silk jacket and black silk pants and said: "To look at him on the runway with all his openness -- you know why you love the Russians." Travel agents are predicting a 60 percent rise in American trips to the Soviet Union by the end of the year, compared with 1986.

"Everything Soviet is suddenly very romantic. Everybody's into it," says Helen Simonson, a spokeswoman for General Tours, a large U.S. tour operator to the Soviet Union.

What's going on here? Only yesterday the Soviet Union was everything grim, gray, brutal and bureaucratic. The Wendy's fast-food people ran a television ad two years ago spoofing Soviet drabness by showing fat fashion models wearing gunnysacks. The image of Russians we'd gathered for years from television and magazines was one of people who looked like cinder blocks wrapped in Value Village overcoats, bleak and stolid in a combination that is communism's unique contribution to cultural esthetics.

If their empire was as evil as Reagan said it was, they were the living proof of its banality. Soviet leaders stared down at parades of rocket launchers with the smug wariness of crooked cops. Soviet vacationers sagged out of bathing suits on Black Sea beaches. Soviet citizens stood fur-hatted in endless food queues, looking like stalled assembly lines of old-fashioned refrigerators with the coils on the top ... There may have been poets and gymnasts and ballet dancers with killer cheekbones, but mostly, a quarter century after Khrushchev said "We will bury you," they looked like out-of-work undertakers, horribly ordinary, reductio ad lumpen.

And why not? What was to admire? Their economy has been falling apart for years, with the growth rate of their gross national product falling from 5.9 percent in the late '50s to a stagnant 2.7 percent in the first half of the '80s. Life expectancy is going down, and infant mortality rates are three or four times as high as they are in the United States. Grain harvests have become annual disasters. Alexander Solzhenitsyn has added a word to the English language: gulag. A nuclear reactor went berserk in Chernobyl and rained radioactivity across Russia and northern Europe. There are 120,000 Soviet troops waist-deep in the big muddy of Afghanistan, Gorbachev announced consideration of troop pullouts a year ago, and nothing much has happened. We learned from Vietnam how that story ends.

Now, even with the thick roster of protests planned around Gorbachev's visit, the atmosphere is changing in one of those great lurches of national feeling that foreigners find both charming and frightening about America. The change may tell us more about America than the Soviet Union.

It was just a year ago August that American journalist Nicholas Daniloff was being framed in Moscow. It was only last February that the KGB was beating up Moscow demonstrators in front of Western television cameras. But Speaker of the House Jim Wright said in May that "relations between our two countries have never been better since World War II." Gorbachev's publisher, Harper & Row, is selling "Perestroika" as "the book of the year by the statesman of the year." People magazine devoted an entire issue to Russia. The suave commentator Vladimir Posner has become a regular on American news shows. In Pittsburgh, Tatiana Vedeneeva, star of the Soviet children's show "Good Night, Little Ones," joined "Mister Rogers' Neighborhood" to tape shows that will appear in March.

On television news, the Soviet people are looking better and better. Princeton Sovietologist Stephen Cohen explains that under Gorbachev, American viewers "are seeing more of the Soviet Union" at the same time that "the gray stereotypes have become more Westernized." Betty Bumpers, president of Peace Links and wife of Arkansas Sen. Dale Bumpers, visited the Soviet Union last month and said, "I don't know whether it's Raisa's influence or the fact that there is a lot more exposure because Americans are everywhere, but the Soviet women are dressing better, their haircuts are better, there is definitely a difference in how they look."

The main attraction, of course, is Gorbachev, who is scheduled to arrive here next week for a summit conference with President Reagan and the signing of a treaty on removing short- and intermediate-range nuclear missiles from Europe, with hints of possible further agreements on arms reduction.

No Soviet leader since World War II has gotten such acclaim. In the 2 1/2 years since he became general secretary, he has become a symbol of Western hope for change in the Soviet Union, thanks to his calls for perestroika, meaning, in his words, "initiative and creative endeavor, improved order and discipline, more glasnost, criticism and self-criticism in all spheres of our society."

Gorbachev, previously known for presiding over one terrible grain harvest after another, has become not just a major world figure but, to some exhilarated journalists, a historical one as well. Los Angeles Times correspondent Robert Scheer writes: "Reading those bold words in the historic National Hotel up the hall from Room 107 where Lenin sat in 1918 looking out at the walls of the Kremlin where his party inexplicably and suddenly held power leaves one wanting to dash out into the streets, like John Reed in the movie 'Reds,' to witness the change."

Henry Kissinger can warn that if Gorbachev succeeds, "the democracies will in the long run be less secure," and Sens. William Proxmire and Bill Bradley can worry about the wisdom of giving trade benefits to an adversary, but these voices are small ones amid the clamor. Some may argue that Gorbachev is a Marxist-Leninist ideologue, but Americans don't like to think in terms of ideology. Besides, since the McCarthy era of the mid-'50s, many people have come to reflexively distrust anticommunism.

The very suggestion of "revolution" -- a word that Gorbachev, as a Russian Communist, does not use lightly -- is thrilling. It does not matter if little has changed in the Soviet economy and Politburo conservatives are hemming in Gorbachev when it comes to issues ranging from criticizing Stalin to allowing the performance of heavy-metal music.

One explanation for the enthusiasm is that Gorbachev, now 56, took power after a seemingly endless parade of infarcted old thugs: Brezhnev, who ruled (along with Kosygin at first) from 1964 until he died in 1982, then KGB boss Andropov, who died in 1984, and then the decrepit Chernenko. But this theory doesn't allow for the possibility that Gorbachev is at least in part a creation of eager imaginations that might have fastened on anybody.

When The Wall Street Journal reported that the Soviet leader "likes Glenn Miller records, good scotch whiskey, Oriental rugs and American books," and a description in The Washington Post had him fond of "cynical political jokes with an anti-regime twist" and said that "he has a record of stepping out of his high party official's cocoon to contact dissidents," they were talking about Andropov, not Gorbachev.

"Western journalists think of power in personal terms," says Dmitri Simes, a Soviet e'migre' and senior associate at the Carnegie Endowment for International Peace. "I am extremely disturbed by it. Gorbachev is the most interesting, intellectual and creative statesman of our time. He is also an intellectual and creative communist. It is a flaw in this country's body politic -- either we demonize completely, or we go overboard with enthusiasm. All populist cultures have a tendency to go from one extreme to another."

Also, there is always a star that burns brightest in the international firmament: Kennedy, Khrushchev, de Gaulle, Mao ... and more recently, to the disbelief of American liberals, Ronald Reagan. Now it's Gorbachev, a man who seems to be beating America at its own game by suddenly accepting proposals for onsite missile inspections (to the alarm of the Pentagon) and edging Reagan out as the Great Communicator. Gorbachev glides through summit meetings with a fiercely focused self-confidence, none of the smarmy, shambling mock humility that major American political figures, particularly Reagan, have affected since the fall of the last conspicuous grown-up to hold the presidency -- Richard Nixon.

Harvard's Adam Ulam has written: "An intellectual often finds a certain morbid fascination in the puritanic and repressive aspects of the Soviet regime and also in its enormous outward self-assurance, which contrasts so saliently with the apologetic, hesitant self-image of the democratic world."

If the Soviet Union, like the United States, presents a utopian vision to the world (however failed or impossible), Gorbachev represents a shift in that vision. In the 1930s, admiring Americans saw the Soviets moving toward the rational, technological utopia that we longed for. In the late '60s, we came to long for another sort of utopia, one that would free us from the constrictions of rationality and machines by unfettering the instincts and appetites that arise spontaneously from natural goodness. This was the way to peace, prosperity and beautiful relationships.

We're not apt to hear Gorbachev saying "if it feels good, do it," no matter how many experts on America become his close advisers, but there's a sense of catharsis in glasnost; we're delighted with whatever spontaneity we can find in him. He gives press conferences! He speaks without notes! His wife dresses with care and pleasure, and tours an exhibit of American art in Moscow, offering opinions on the paintings! He echoes our intellectuals' pet doctrine of the global village when he speaks of "interdependence."

With his smiles, his ad-libbing and even the birthmark on his head he seems more human than any Soviet leader since Khrushchev. It's possible to think of him as a man who could change the world, this being an age when we think of our futures being determined not so much by individuals as by trends, cycles, or, in the canon of Marxism, the dialectic of history itself. And in the backs of some minds must lurk the question: What if he made communism work?

After long years of Cold War and nuclear jitters, there is also the imminent signing of the INF treaty to celebrate. In the name of peace, the same bartenders who were pouring Stolichnaya vodka in the gutters after the Soviets shot down a South Korean airliner in 1983 (killing an American congressman) are serving it again.

"I woke up in the middle of the night and asked, my God, what would happen if they agreed, hands across the water, to ban nuclear weapons and I didn't have it," says Mo Sussman, of Joe and Mo's restaurants.

What would happen if they agreed? This is the '80s equivalent of the '60s question: What if they gave a war and nobody came? What a thrilling thought! America goes through spasms of terror over nuclear war. They come and go. In 1959, for instance, two-thirds of Americans thought the threat of nuclear war was our biggest problem, and five years later only a sixth said so. In the early '80s, when the nuclear freeze movement and movies such as "The Day After" were prominent, 47 percent of Americans regarded nuclear war as very or fairly likely, according to polling analysis from a nonprofit organization called Americans Talk Security. Now, says the group, the comparable figure "stands at 30 percent. As we look to the late 1980s, we may find that real prospects for nuclear arms reductions will do more to mobilize political support for arms control than will attempts to heighten public concern about the possibility of a nuclear outbreak."

"I really want Gorbachev to be for real," says Jessica True, 18, a salesperson at Commander Salamander in Georgetown, which offers a variety of Soviet-inspired T-shirts, hammer-and-sickle suspenders and earrings, red-star pins and Persian-lamb hats. "People are freaking over the Persian Gulf, and they want the bombs gone."

Was it this passion that Raisa Gorbachev perceived when, according to one Soviet official, she urged her husband to "go over the head" of Reagan and direct an appeal straight to the American people?

Few things inspire Americans as much as the vision of the peaceable kingdom where the lion lays down with the lamb, paradise regained, Rousseau-ian noble savagery vindicated at last. (It's worth noting Woody Allen's Corollary here: The lion will lay down with the lamb, but the lamb won't get much sleep.) Paul Hollander, a sociologist at the University of Massachusetts and the Russian Research Center at Harvard, writes in "Soviet and American Society" that "although there is little substantive similarity between the ideals of the Puritans and 18th-century American revolutionaries, and the Russian revolutionaries of the 19th and 20th centuries, the attitudes of these diverse groups have an important, if obvious, common core: The belief that it is possible to alter society fundamentally, that radical new departures in human affairs are feasible and that accumulated historical antecedents of injustice, oppression and privation can be undone by human will and exertion." In "Mr. Sammler's Planet," Saul Bellow writes: "Both the U.S.A. and the U.S.S.R. were, for Sammler, utopian projects."

The Americans have been pinning hopes on the similarities of these very dissimilar countries since the early years of the Soviet Union. Businessmen see a nation of businessmen, American politicians look for their equivalents, rock 'n' rollers cite the black market value in Moscow of Elvis Presley records.

A British journalist named Claude Cockburn has recalled that in the years 1929-30, "Wall Street men ... looked upon the USSR with a minimum of alarm, as in effect just another fast developing area with a big trade potential." He added: "There was something undeniably irksome in the American evaluation of the situation -- as though the Revolution and the doctrines of Marxism-Leninism were puerile incidents, temporary deviations from the ultimate forward movement of the world alongside business-like American lines." In 1946, William Barrett said that fellow travelers "would love to believe that Russia is capitalist at heart." In 1984, when Gorbachev visited Great Britain, Margaret Thatcher set Western hearts going pitapat yet again. "We can do business together," she said.

We have yet to do much business, but by now the sentiment is a tradition, a standby to be brought out when relations with the Soviet Union thaw periodically.

This way of thinking, known as the "convergence theory," looks for similarities wherever it can find them. Tip O'Neill met Gorbachev in Moscow and found him "easy and gracious. He is like one of those New York corporation lawyers." The New York Times reported that he "left several senators feeling as if they had met an American-style politician."

How we crave a world in which everyone is the same -- just folks! How many barrooms have rung with the proposal that "We oughta get our guy and their guy out there toe-to-toe and let them settle it" -- as if any differences could be settled by a scuffle between the pickup trucks.

The flip side of the fistfight is a seduction, stemming from the notion that if the Soviets only knew what America is really like, if they could hang out in enough shopping malls, if they could attend a Fourth of July family picnic in Iowa, or a town meeting in New Hampshire, they'd be converted instantly -- hence everything from jokes about destroying Soviet repression by bombarding their country with rock cassettes and marijuana to President Reagan's repeated desire to have Gorbachev visit his ranch in California, to see how good American life can be, or to fly him over the pool-jeweled neighborhoods of Los Angeles and say that these are the houses of "the workers." We might call this the Ninotchka Hypothesis, after the 1939 movie in which Greta Garbo, playing a Soviet commissar, succumbs to the temptations of the West.

"Nothing is more difficult to convey to an American audience," writes Sovietologist Richard Pipes, than the fact that "Soviet society and its political culture are significantly different from those familiar to Westerners ... This belief in the identity of human nature and human interests and the view that conflict is rooted in ignorance, prejudice and misunderstanding is the source of the widespread belief that if the American and Soviet leaders only got together they could solve all the problems dividing their countries."

Ultimately, our response to Gorbachev and the Soviet Union tells us at least as much about ourselves as it tells us about them. Other countries react to Gorbachev in some of the ways we do, as in rioting kids in East Berlin chanting Gorbachev's name as a symbol of freedom when they listened to a rock concert across the Berlin Wall last June. But there's something particularly American in the eagerness of our idealism.

"If you look at American public reaction, it tells you nothing about what's going on in Russia," says Princeton's Cohen. "In the 1930s, under a terrible regime, there was a lot of American admiration for the Soviet Union. By the 1970s, when things were better, you couldn't find anybody who admired it. We use the Soviet Union as a justification for things we do. We compare Central America to Afghanistan, we compare Three Mile Island to Chernobyl. It always puzzles me why we define ourselves by anything in the Soviet Union."

But we do -- call it bridge building, good business, convergence or the "moral equivalence" that conservatives point to.

In the late '50s and early '60s, a combination of the Soviets putting up the first satellite, Sputnik, along with the outrageous charisma of Khrushchev and the terror of the Cuban missile crisis, led to an analogous outbreak of fascination that led to a jump in Russian language studies, the belief that the Soviets were vastly ahead of us in scientific research, and a popular song called "Dear Ivan," expressing the undying American belief that folks are just folks, the world around, and if we could just sit down together and swap baby pictures, there'd be peace.

At the same time, the Soviets may be turning around and taking their cue from us.

"When America declares somebody big, who else can say he is not big?" asks Milan Svec, a former official of the Czech Embassy here who now works at the Carnegie Endowment. "With your reaction to Gorbachev, you are saying that for the first time you have an intellectual challenge. He forces you to build his personality cult. You don't think Russians love it that at last they have somebody who is respected in France and America?"

On our side, at least, the cult of Gorbachev will last until the next airliner gets shot down, the next tanks roll into Poland or Hungary, the Cuban mercenaries get shipped to yet another Third World country, and then we'll set about inventing the Soviet Union all over again.