French feminist icon Simone de Beauvoir's "mad passion" for a lover 18 years her junior has been revealed in a letter published for the first time Sunday.

It also shows that she was never sexually satisfied by her partner, the existentialist philosopher Jean-Paul Sartre.

The writer, who condemned marriage as an "obscene" institution which enslaved women in her classic book, "The Second Sex", wrote to the film-maker Claude Lanzmann in 1953 saying she would throw herself into his "arms and I will stay there forever. I am your wife forever."

The note is one of 112 love letters written to the only man de Beauvoir ever lived with, which has been bought by Yale University.

It reveals that Sartre -- who had many other lovers and always kept a separate apartment -- was never able to satisfy her physically in the same way.

"I loved him for sure," she wrote to Lanzmann, "but without it being returned -- our bodies were for nothing."

Nor did she find the same bliss in bed with the American novelist Nelson Algren, author of "The Man with the Golden Arm".

"I loved him because of the love he had for me, without any real intimacy and without ever giving to him from inside of myself," she added.

Lanzmann was 26 and Sartre's secretary when the pair met. De Beauvoir was 44.

The golden couple of French intellectual life had a famously open relationship, and enjoyed -- and endured -- a number of similar love triangles.

- Feud with daughter -

Lanzmann, now 92, who went on to make the acclaimed Holocaust documentary "Shoah", told Le Monde newspaper that the full story of their love was only coming out because of a clash with Beauvoir's adopted daughter.

He accused Sylvie Le Bon de Beauvoir -- who under French law will hold the copyright to the letters on his death -- of trying to write him out of her mother's life.

Le Bon was de Beauvoir's last lover and companion and remains her literary executor.

Fearing that Le Bon wanted to "purely and simply eliminate me from the existence of Simone de Beauvoir", he sold the letters to Yale so that historians would have access to them.

Lanzmann said he never had any intention to make them public until he realised that Le Bon was going to "publish all de Beauvoir's letters except the correspondence between her and me."

He feared he would die and no one would know about the letters.

The film-maker has previously written of their "mad passion" in his memoir "The Patagonian Hare", but the existence of such a torrid correspondence was not known.

In de Beauvoir's letter from Amsterdam published by Le Monde, she writes, "My darling child, you are my first absolute love, the one that only happens once (in life) or maybe never.

"I thought I would never say the words that now come naturally to me when I see you -- I adore you. I adore you with all my body and soul... You are my destiny, my eternity, my life."

- Open relationship -

Lanzmann, who edited "Les Temps Modernes", the ground-breaking review de Beauvoir and Sartre founded after World War II, insisted that it wasn't a menage a trois. "We weren't a trio. I had a relationship of my own with Sartre."

It was a complicated one, however.

"Sartre fell totally in love with my sister Evelyne Rey when he saw her acting in (his play) 'No Exit'", the drama with his famous line "Hell is other people".

"Also on stage that night was my first wife Judith Magre," he added.

Le Bon de Beauvoir could not be contacted by AFP. Le Monde said she did not reply to their requests for an interview.

Lanzmann believes she holds his letters to de Beauvoir and that she made sure he was not invited to the unveiling of a plaque on the house where he lived with de Beauvoir for eight years.

Agnes Poirier, author of "Left Bank", a new book about how "the ideas that shaped the modern world" were formed in the French capital during the tumult of the 1940s, said Lanzmann always maintained de Beauvoir was a "'grande amoureuse', a very passionate lover."

"After the age of 40 de Beauvoir thought she was not desirable anymore but she had a second youth with him," Poirier said -- and she lived it "like a rebirth".

"They would work together in the mornings, then in the afternoons she would go and write with Sartre."

Just as with Sartre, it was an open relationship "but de Beauvoir took it badly when she discovered that Lanzmann had had an affair he didn't tell her about."

The letters can now be consulted only by researchers at the Yale University library

Source: AFP