Music blared, drums beat a menacing rhythm and protesters stood behind banners proclaiming their opposition to President Sarkozy on May Day marches in Paris this week.

Leaning on a roadside railing, Adrien Derain sought to motivate his comrades with a slogan scrawled on a piece of cardboard hung around his neck. “Mai ’68, Mai 2008”. It was a call to arms in a society permanently on the edge of conflict – an invitation to the next round in the centuries old fight between les autorités and les contestataires.

As students such as Mr Derain listed their grievances – threats to teaching staff, unemployment and concerns over pensions – they emphasised the gulf that separates today’s France from the riots of 40 years ago.

Then, the country exploded in search of a better future. Now, instead of revolution, demonstrators want pragmatism and stability – to stop things from getting worse. “This has nothing to do with May 1968,” the 17-year-old said. “We’re in a different world.” That may explain why France has embraced the anniversary of the greatest upheaval in its contemporary history with such awe and nostalgia.

The legacy of May ’68 is controversial. It was, though, a time of optimism and dreams – both of which are in painfully short supply four decades later. More than 100 books have been published about the month-long rebellion, which pushed the country into a modern world of sexual liberation and individual freedom. At least 120 exhibitions have been organised, 30 or so symposiums, 45 television and radio shows and countless press articles.

The turmoil that year was by no means limited to Paris. There were protests in London, Berlin, Prague and across the US as opposition grew to the war in Vietnam. Nowhere was the clash between generations as intense as in France, where the Latin Quarter exploded into violence before spreading to become a general strike involving ten million workers.

It all began in Nanterre University, on the outskirts of Paris, when student activists challenged the established order by demanding the right for men to go into women’s dormitories. “It was an incredibly puritan world,” Daniel Cohn-Bendit, then a 23-year-old student leader, said.

François Misoffe, the Minister for Youth, responded by offering to build a swimming pool in the university. “What’s all this about a pool?” Mr Cohn-Bendit said. “Because the problem of today’s youth is sexuality. If you’ve got problems, go and jump into the swimming pool to calm yourself down,” Mr Misoffe retorted.

Their exchange set the mood for a movement that plunged France’s paternalistic authorities into bewilderment as protesters grew long hair and shed ties. “They’re telling us something we don’t understand,” General Charles de Gaulle, France’s wartime hero and postwar President, said. Even most of the students were unsure of the meaning of their uprising.

Many wanted a new political order – a proper, grown-up Revolution like that of their ancestors in 1789. “We tried, but we met the limits of that exercise,” Mr Cohn-Bendit, 63, now a Green politician, wrote in his book Forget 68. “It lasted a month.”

If French politics stayed the same, society underwent changes that affected schools, culture, families and sexuality. Marcel Gauchet, a philosopher, said that France had yet to grasp the extent of “the immense anthropological mutation” set in motion by May ’68. For the first time the nation that emerged from the rebellion was no longer organised to ensure its own reproduction, he said. “This really was a revolution – but not the one they thought they would provoke.”

Detractors say that the consequences have been disastrous – divorce, drugs, crime and a general breakdown in social cohesion amid the pursuit of individual happiness. Mr Sarkozy was virulent in his criticism, pledging to “liquidate the legacy” of the uprising during his election campaign last year.

He is in a minority. According to a recent poll 80 per cent of French people think that May ’68 had a positive influence on relationships between men and women. More than three quarters would join the students on the barricades if it happened again.

Mr Cohn-Bendit said that Mr Sarkozy was a beneficiary of the movement – a liberated divorcé whose latest wife, Carla Bruni-Sarkozy, counts Mick Jagger among her conquests. “Without the emancipation of the 1960s Sarkozy could never have been President,” Mr Cohn-Bendit said. “De Gaulle and his wife must be turning in their graves.”

For today’s student generation, however, it is time to get real. “We’ve got to stop dreaming,” Alexandre Bertrand, a 21-year-old law student, said. “What we need is more pragmatism. You can’t ask for the impossible.”

Slogans of revolt

— It’s forbidden to forbid

— Imagination in power

— Under the cobblestones, the beach

— Everything, immediately, always.

— I’m a Marxist, Groucho tendency

— Be realistic, ask for the impossible

— I decree a state of permanent happiness

— Dreams are reality

— Unbutton your mind as often as your flies

— Live without dead time, jouir without restraint

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