Chamber music graced fashionable Right Bank boulevards. On the more avant-garde Left Bank, novices tooted penny whistles and children banged saucepans. For one night, all of Paris was turned into a concert hall.
All the different melodies made up the first ''fete de la musique,'' a recent experiment by Culture Minister Jack Lang that typifies how he is trying to put a strong socialist stamp on French culture.
Mr. Lang hopes to use the government as the catalyst of a cultural renaissance here, restoring France to what he sees as its proper role as a center of world culture. At the same time, he aims to wrest music, art, literature, and theater from the nearly exclusive patronage of the Paris bourgeoisie.
''We want everybody involved,'' exults Lang's adviser, Veronique St. Georgs.
To achieve these goals, the Socialist government is spending a lot of money. France's culture budget was doubled this year, bringing it to $1.1 billion.
And increases will continue, though not on as grand a scale as originally envisaged because budget cuts are being demanded from every ministry in an effort to close the mounting government deficit.
Spending more money to listen to music in the streets seems a pleasant and innocuous initiative. And at first glance, so does everything about Mr. Lang. He looks far younger than his 39 years, and he projects enthusiasm and energy as he wings about the country promoting his policies, often casually dressed with his long, curly black locks flying about.
But Mr. Lang is a Socialist militant who sees culture as a deadly serious political weapon. Last week at a UNESCO meeting in Mexico, he called for a ''crusade'' against American ''cultural and financial imperialism.'' He declared war on ''the invasion of fabricated images, prefabricated music, and standardized productions which are destroying national cultures.''
In Mr. Lang's view, culture is a ''commodity'' to be fought over. Ironically, his conservative predecessors felt much the same way. Previous French governments vigorously promoted French culture - its language, art, and literature - overseas by subsidizing such institutions as the Alliance Francaise.
At home, Mr. Lang's ideas about culture have led him to take more controversial actions aimed at breaking the Anglo-Saxon stranglehold over popular music and film. Claiming American films didn't need his help, he boycotted an American film festival last year at Deauville.
Briefly, too, Mr. Lang toyed with the idea of putting quotas on the number of American tunes radio stations and discotheques here could play. But a survey carried out by his own ministry showed that many discotheques would go broke if they played more French pop.
Instead of quotas, Mr. Lang finally decided to spend money subsidizing the development of French music. Music education is being increased throughout the country, and the national conservatory is being enlarged and relocated.
A similar approach is being used in trying to reduce the American influence on French television, where according to a Culture Ministry report, a majority of films now shown come from Hollywood. The Culture Ministry has begun subsizing French filmmakers in an attempt to restore the spirit and adventure in France's lackluster film industry.
But many critics question whether state intervention can really invigorate culture. You can't decree a good tune or a brilliant film director, they argue.
''I don't think government plays that big a role in stimulating culture,'' says Pierre Mazars, chief art critic for the daily Le Figaro. He fears that Socialists will spend money developing better bureaucrats rather than better artists.
Mr. Lang's attempt to remove French culture from what he calls the exclusive grasp of Paris's haute bourgeoisie is also criticized for helping the amateur at the expense of the professional. Musicians from the Paris musicians' union, for example, didn't participate in the recent street-music festival.
Such events are ''deprofessionalizing,'' complained Francois Nowaks, secretary-general of the union. ''The Socialists are not helping professional artists achieve a better social status.''
Still, no one denies that in only a little more than a year in office, Mr. Lang has shaken up the French cultural world, a world that has grown largely stale with the great exception of the innovative and successful Georges Pompidou Center, known as the Beaubourg.
To the wonderment of many, Mr. Lang made the Comedie Francaise put on acts in the Paris Metro. And a new ''popular opera'' house seating 4,000 is scheduled to be constructed at the Place de la Bastille, an appropriate site since that is where the people began their uprising against Louis XVI in 1789.
Most of the extra money budgeted for the Culture Ministry, though, is being used for developing culture in the provinces. Numerous Parisian troupes have received government money to tour outside the capital.
But in the provinces, the ministry's primary aim is to promote home-grown talent. In dance, a ballet school has been established in Marseilles, and a conservatory in Lyon. Folk dancing has been revived in public schools.
New art schools are being set up throughout the country in an effort to make up for France losing out to America and Britain as modern art centers. State funds for buying art for museums, with an emphasis on those outside Paris, were increased 10 times this year.
Finally, Mr. Lang is encouraging reading by putting price controls on books and establishing more public libraries. ''Do you realize that there are only 76 public libraries in all France now?'' asks Mrs. St. Georgs.
But the results of these programs will not be known for a long time. Meanwhile, Mr. Lang has had nothing to do with the biggest cultural hits in Paris this summer.
First, there was Polish exile Roman Polanski playing Mozart in Englishman Peter Schaeffer's play, Amadeus. Then the American pop duo Simon and Garfunkel charmed more than 150,000 Parisians with two packed open-air concerts.
Finally, veteran Frenchman Yves Montand is wowing audiences. After more than a decade of preoccupation with films, he has returned to the art that made him famous - singing. Tickets to his show at the Olympia music hall are sold out.