After a generation of conservative rule, it seemed like a new political dawn. The Place de la Bastille, symbol of the French left ever since the storming of its royalist prison by a revolutionary mob in 1789, was packed with ecstatic Parisians waving red flags and chanting, "We have won."

Among the crowds celebrating the Socialist election victory on May 10, 1981, was Jacques Fansten, a film director whose vaguely left-wing sympathies mirrored the attitudes of many leading cultural figures. He went back to the Bastille recently to shoot the opening scenes for his new film, "States of Mind," which traces the political disappointments and shattered dreams of many of the people who danced in the rain five years ago.

The closing sequence of the film will be shot in a television studio on Sunday evening as results come in from France's parliamentary elections. If everything goes as Fansten expects and the opinion polls unanimously predict, it will depict the return of the right to power after the longest period of left-wing government that France has known since the 1789 revolution.

Still unclear is what will happen to Francois Mitterrand, France's first Socialist president in more than a quarter of a century. He could hang on for the remaining two years of his seven-year mandate, seeking to "cohabit" with old political opponents. Or, if he feels he has been stripped of too much power, he could resign, forcing early presidential elections. In either case, the left-wing adventure that began with his election in 1981 has effectively ended.

Both France and the French left have changed since Mitterrand's election triumph. The euphoria of the political honeymoon has long since vanished. Old ideological certainties have disintegrated in the face of harsh economic reality. Even the terms "left" and "right," which were invented in France to reflect seating arrangements for political factions in the revolutionary assembly, seem less important as political consensus takes over.

"Five years of socialism have changed the behavior and way of thinking of half of France," noted Fansten. "When your side arrives in power, you quickly discover that changing things is not as easy as you previously thought."

Socialist campaign promises in 1981 to "break with capitalism" and apply a "different logic" to solving the country's economic problems make strange reading now.

These days, Socialist ministers are eager to stress their competence, not their imagination. The color red, with its ideological overtones, has virtually been banished from Socialist election posters.

The mood of the campaign, with its emphasis on pragmatic themes like tackling inflation and bringing down unemployment, was captured in a front-page banner headline in Liberation, an irreverent but intelligent left-wing newspaper: Vive l'Ennui -- "Long live boredom." It could almost serve as a slogan for a society intellectually exhausted by competing visions of utopia.

"France is no longer divided into two fiercely opposed nations," said Alain Touraine, a sociologist. "We may finally be seeing the end of politics as a kind of war of religion or civil war, with left and right pitted against each other like north and south. As far as this particular campaign is concerned, the political parties might as well have been selling shirts or detergents."

Regis Debray, a French writer who joined Che Guevara in the Bolivian jungle and now advises Mitterrand on foreign affairs, agreed:

"After five years in power, the left has succeeded in making the transition from a culture of opposition to a culture of government. I only hope that this is also accepted by the right. Up until now, right-wing politicians have tended to behave as if they had an exclusive right to rule the country."

In a recently published interview with the novelist Marguerite Duras, Mitterrand depicted France as a "generally conservative" country that experienced only occasional spasms of passion for the left. One of his main aims since 1981, he declared, was to allow the left to govern for extended periods of time.

By Mitterrand's count, the left has only been in power in France four times since the 1789 revolution. In 1848, when liberal ideas swept through Western Europe, a popular government came to office for four months before being toppled by a military coup following bloody riots. The Paris Commune of 1870 was crushed after only two months. The Popular Front of 1936 fell apart within a year.

Some historians dispute the president's simplified version of history, arguing that left-wing political parties were associated with a series of governments under both the Third and Fourth Republics. Mitterrand was a minister eight times in the 22 Fourth Republic governments between 1946 and 1958. It remains true, nonetheless, that what Mitterrand terms "the obscure will of the French people" has generally favored the right.

Thus, while France may have provided the world with some great revolutionary theater, it has also been very effective at clearing the stage afterward. Take, for example, the 1968 student upheavals in Paris, which were followed, within a couple of weeks, by one of the biggest right-wing electoral landslides this country has witnessed.

That the Socialists were able to remain in power this time for five years, the full length of a parliamentary term, was due in part to the Gaullist institutions once ferociously attacked by Mitterrand. The combination of a strong, directly elected president, introduced by Gen. Charles de Gaulle in 1962, and the solid pro-Mitterrand majority in the National Assembly insulated the Socialists from the frequent political crises that toppled previous left-wing administrations.

Paradoxically, France has probably become a more conservative country during the past five years of left-wing rule. The failure of the Socialist government's attempts to buck the worldwide recession by reflating the economy in 1981 and 1982 converted many skeptics to the virtues of sound economic management. The spectacle of large-scale nationalizations boosted the popularity of free market ideas.

Marxism has practically withered away as a serious intellectual force. The Communists, who served as a junior partner in the Socialist-led coalition until quitting in disgust in 1984, seem locked into apparently irreversible decline.

"The left was able to last for five years by implementing policies that were not its own," remarked Rene Remond, one of France's leading political scientists. "Once they got into power, the Socialists were converted to ideas that they had previously suspected: the importance of private enterprise, the profit motive, and so on. To replace the idea of socialism with the idea of modernization is an enormous change."

Looking at France socially rather than politically, there has also been a swing back to traditional values. What has been called the "1968 generation," the rebellious students who erected barricades in the streets of Paris, is now composed largely of respectable middle-class parents. Their own children tend to be more interested in passing exams and thinking about a career than making a revolution.

The most significant mass movement to take place in France under the Socialists was profoundly conservative: the groundswell of public opposition to the government's plans to restrict the independence of Catholic schools. The protests culminated in a massive demonstration by more than a million people in June 1984 that ended up at the very same Place de la Bastille where joyful crowds had acclaimed Mitterrand's victory three years earlier.

Forced to drop the proposed reforms, Education Minister Alain Savary resigned.

"A conservative wind is sweeping much of the western world. It is blowing with more force in France than in neighboring countries," he commented a few weeks later. His successor, Jean-Pierre Chevenement, the leader of a left-wing Socialist Party faction known as CERES, quickly set about imposing a "back to basics" regime on the classroom.

On the industrial front, the trade unions are probably less powerful than at any time in the last two decades. The discipline of rising unemployment and the absence of any political alternative to economic austerity have resulted in a sharp fall in the level of industrial unrest. Figures released by the Ministry of Labor show that the number of working days lost through strikes has been lower under the left than it ever was under the right.

In foreign policy, the Socialists turned out to be more Atlanticist than their conservative predecessors. Initial U.S. reservations about the presence of four Communist ministers in the Cabinet were quickly offset by delight at Mitterrand's tough attitude toward the Soviet Union. The president strongly endorsed the deployment of U.S. medium-range nuclear missiles in Europe in 1983 at a time when several of his comrades in the Socialist International were expressing support for pacifist demonstrations.

Mitterrand, who opposed de Gaulle's efforts to develop a French nuclear bomb in the 1960s, was persuaded to accept the logic of nuclear deterrence in the '70s. In office, he has become an enthusiastic apostle for the bomb, the ultimate symbol of a French president's authority.

The political contortions have had differing effects on the left-wing activists who greeted Mitterrand's election in 1981 as the coming of a new age. A typical cross section is provided by Fansten's film, "States of Mind," which uses the device of five friends who meet at the Bastille celebrations to chart the confrontation between dreams and reality.

The first to become disillusioned is a sociologist, an antinuclear Socialist theoretician. Three months after his appointment as an adviser to the new minister of energy, the decision is made to proceed with a huge nuclear program launched by the former right-wing president, Valery Giscard d'Estaing. The sociologist shuts himself up in his office for four days but finally decides against resignation.

"Being in power gives you no more than a 5 percent freedom of maneuver, but that is enough to make it worthwhile," he argued.

A tax inspector who has long dreamed of "making the rich pay" quits in 1984 when he discovers that he is out of touch with his superiors. A schoolteacher has a nervous breakdown after Chevenement's appointment as minister and the declared return to the old values. A television journalist becomes cynical when he sees all his colleagues scrambling aboard the new political bandwagon. A theater director is appointed to open a new cultural center in the provinces, but is frustrated by the lack of public support for his experimental ideas.

The moment of truth for Mitterrand arrived in March 1983 when he spent 10 days closeted with his advisers in the Elysee presidential palace, agonizing about France's economic future. The state coffers were empty and the foreign trade deficit had widened to alarming proportions. His eventual decision to reject the protectionist option has been hailed by many French commentators as the most important single decision of his presidency.

Unemployment shot up as the result of the harsh austerity measures the government was forced to embrace. But French industry was exposed to the bracing winds of international competition and the long-term dynamism of the economy was strengthened.

"The real watershed came not in 1981 with the change of government but in 1983 with the change of economic policy," remarked Serge July, the editor of Liberation and author of an acclaimed book on "The Mitterrand Years."

In July's view, the economic conversion that France underwent under Mitterrand is comparable to de Gaulle's accomplishment in granting Algeria independence in 1962. Just as it required a right-wing president to persuade the French to sacrifice their prized North African territory, so it took a left-wing president to persuade them to give up many of their cherished economic illusions.

Until 1982, the Socialists put the emphasis on fulfilling the left's election program: abolition of the death penalty, a cut in the retirement age, a 39-hour work week, increased social security benefits, an extra week of paid vacation, and the nationalizations of all the major banks and five leading industrial groups. After 1983, France's economic modernization became the overriding priority.

Mitterrand's real achievement, July argues, was to help turn France into a more "normal" society. By breaking the string of right-wing governments, the Socialist election victory brought France into line with the Anglo-Saxon tradition of well-organized parties taking turns in power. France has become a more open society over the past few years.

There are many French rightists who would never dream of voting Socialist but who are willing to concede that the exercise of power by the left has been both positive and necessary. Had the right tried to impose the harsh economic medicine that was eventually administered by the left, it is argued, France might have been torn apart by a violent social explosion.

If these political sophisticates find fault with Mitterrand, it is that he initially misinterpreted his slim election victory in 1981 as a mandate for sweeping change. In fact, it was more a vote against Giscard, many of whose supporters had been alienated by his haughty ways and tarnished political image.

"The electorate has not forgiven the Socialists for promising more than they could deliver," remarked Remond, criticizing the left for its initial, unrealistic spending spree. Michel Sainte-Marie, an outgoing Socialist deputy from Bordeaux, disagreed.

"We were obliged to try to keep faith with our supporters. Otherwise, there would have been tremendous cynicism and Mitterrand's presidency might have been threatened," he said.

Some time after the great U-turn of 1983, Mitterrand amused himself with the thought of what might have happened had he chosen differently.

"I could have been Lenin," he is reliably reported to have joked to visitors.

The phrase encapsulates the drama of democratic socialism, particularly as practiced in France. Drawing inspiration from 19th-century Marxist ideas as well as France's humanist traditions, the Socialists started out with the dream of accomplishing a radical transformation of society. But they quickly reached a point at which it was necessary to choose between socialism and staying in power.

In the case of the French Socialists, there was never much doubt about the final outcome. With his almost mystical attachment to France -- its countryside, its history and its language -- Mitterrand was no Lenin.

"We have always been the black sheep in the Socialist International because of our support for nuclear weapons and opposition to pacifism," said Debray, long considered one of the most internationally minded of France's left-wing thinkers. "We are more French than we are Socialists."

In his interview with Marguerite Duras, published in a left-wing literary magazine in the heat of the parliamentary election campaign, Mitterrand revealed that he is aware of the contradiction between ideological purity and practical politics.

"How to win? I wish the left would ask itself this question occasionally," commented the first Socialist president of the Fifth Republic.

The remark could almost serve as an epitaph for an extremely able politician who, whatever happens on Sunday, has already provided the French left with a taste for power that could prove addictive.