By James Mackenzie

PARIS (Reuters) - Forty years after May 1968, France is enjoying a wave of nostalgia for the student revolt that rocked the streets of the Latin Quarter in Paris, fuelled by a never-ending debate about what it all achieved.

Countless magazine supplements have shown the fashionably dressed student stone-throwers confronting phalanxes of helmeted police, and radio stations have replayed the breathless live reports that brought the riots directly into French homes.

Television debates have pitted supporters who say the 1968 protests helped free up a hidebound society against critics who say they undermined vital institutions and opened the way to social breakdown.

For some it has all been too much. Daniel Cohn-Bendit, the undisputed hero of the movement, called a recent book of interviews on the subject "Forget 68".

"All commemoration is stupid," Andre Glucksmann, another leading member of the 1968 generation told Reuters, "Either you glorify May 1968 or you vituperate against it."

Sparked by a dispute over visiting rights to a female students' dormitory, the protests over university reforms and wider personal liberties led to three weeks of riots and sit-ins in the streets around the main Paris university, the Sorbonne.

The crisis, which blew up into a general strike that paralysed the country, was so serious that President Charles de Gaulle made checks to ensure the army would be ready to intervene if necessary.

Kept alive by the perennial French fascination with revolution and street protests, the events have divided the country ever since.

"LIQUIDATE 1968"

Behind the confrontation, the surreal humour and idealism of the students, summed up in slogans such as "Sous les paves, la plage" ('Under the paving stones, the beach') and "Never work", remain the strongest image of the 1968 protests.

Opposed equally to the conservatism of de Gaulle and a communist party they attacked as "Stalinist", the students were looking for something traditional politics did not offer, Glucksmann said.

"It was very happy, very cheerful," he said. "But for me, it wasn't about enjoyment, it was above all, a search for truth and when you discover truth, it's astonishing, it's joyous."

But many conservatives say the carefree picture of youthful protest hid a malign disrespect for social institutions that has spawned ills ranging from high divorce rates to the violent riots that hit France's poor multiethnic suburbs in 2005.

President Nicolas Sarkozy has been the most prominent recent critic, pledging during last year's election campaign to "liquidate the heritage of May 1968" and restore respect for traditional values.

Sarkozy's attack has been derided by many who point out that he himself -- thrice married, most recently to an Italian fashion model -- could never have become president in the conservative world before 1968, when a woman still needed her husband's permission to open a bank account.

But many veterans of the movement also acknowledge that the utopian vision behind the protests, while enormously powerful in many ways, was politically impractical.

"It marked society profoundly. Society has taken up all the good things about 1968," said Peter Schneider, a German writer who was a prominent activist at the time. "But politically, thank God, it was a failure. We can count society lucky that we never got the chance to seize power," he said.