Bare buttocks are not something that usually disturb the French. Pink bottoms leer from almost every chemist's window in Paris.
The publication this week of a female bottom on the cover of a serious news magazine, Le Nouvel Observateur, has caused, nevertheless, something of a stir. The bare bottom belonged to Simone de Beauvoir, writer, philosopher and seculargoddess of feminism, who was born 100 years ago today.
One feminist organisation complained that, by illustrating the centenary of Mme de Beauvoir's birth with a nude photograph taken in 1952, the intelligent, centre-left magazine had "assaulted the dignity of women".
Sixty years after she wrote one of the most influential feminist books, Le Deuxime Sexe, Simone de Beauvoir has managed to become a "cover cutie". Are women still regarded as the "second sex" in France?
Florence Montreynaud is one of France's best known feminist authors. She has written about the unusual lifelong love affair and friendship between Beauvoir and the existentialist philosopher, Jean-Paul Sartre.
"My first thought on seeing the magazine was that they would never have considered putting a picture of Sartre's bottom on the front of Le Nouvel Observateur," she said. "Luckily, perhaps. Then my second thought was 'what a fine bottom'. No male philosopher I can think of would have had such a lovely bottom. Mme de Beauvoir had a brilliant mind. She also had a wonderful body. Women win on both counts."
One hundred years after Beauvoir's birth, the cause of sexual equality has made substantial progress, even in France. It remains, however, a tricky subject, especially there.
Mme Montreynaud says that the apparently "relaxed" relationship between the French sexes cloaks a thoroughly male-dominated world. The advance of Sgolne Royal to the pinnacle of a serious (failed) presidential candidate hides a political system in which only one parliamentarian in eight is a woman.
The presence of a woman, Anne-Marie Idrac, at the head of the state railway company, the SNCF, disguises a business culture in which only one in six of all executives, but eight out of 10 shop assistants, are female.
How much influence did Simone de Beauvoir really have? How important a figure is she to young French women today?
Sartre and Beauvoir, the celebrated pair of anti-American thinkers, friends and sometime lovers, are buried in the same grave in Montparnasse. They have suffered an ironic common fate. Both are now studied more eagerly in left-wing and feminist academic circles in the United States than in France.
All the same, the centenary of Beauvoir's birth has produced a flurry of new books, radio and television programmes and magazine articles, and an academic conference in Paris this week. The level of interest has not equalled the commemoration of the Sartre centenary three years ago but it is not far behind.
Serious students of Beauvoir's thought, both French and American, complain that the centenary has been dominated in the French media by a prurient re-examination of her life and loves, rather than her works.
This somewhat misses the point. Even more than Sartre, who was after all a man and expected to do as he wished, Beauvoir's life was her work. She became an iconic figure for feminists all over the world, partly because she practised what she preached. Or at least she seemed to do so.
The Nouvel Observateur headline beside the nude photograph "Simone de Beauvoir, la scandaleuse" is a deliberate tease, but it is also true.
Huguette Bourchardeau, 73, a former environment minister and author of a new biography of Beauvoir, says: "She had enormous influence on women of my generation and those which followed. When I was young, I was impressed by her theoretical work but also by her way of life ... She was like an open window ... she struggled to free herself from conformism and to play the card of freedom."
The Simone de Beauvoir legend is largely but not entirely based on her unusual relationship with Sartre. The couple had a bizarre love affair in which they never lived together and probably never slept together in the last 30 years of their lives (until they were buried together upon her death in 1986).
Each allowed, and even encouraged, the other to have "contingent" flings with other lovers, so long as they discussed at length what had happened later. A book published by one of Beauvoir's former pupils in 1993 revealed that, as a young philosophy teacher in the 1930s and 1940s, she had often seduced her female pupils and passed them on to Sartre. She had also slept with Sartre's male students.
Whether all of this amounts to "feminism" or "existentialism" or just a kind of perverse selfishness is open to question. And yet the relationship between the two the "Fred and Ginger" of existentialism according to one French magazine was sincere. At least on Beauvoir's side. When Sartre died in 1980, she threw herself, distraught, on his grave. She had once said: "Whatever happened between us, I knew that he could never hurt me, except by dying."
She also once said: "My greatest achievement was my relationship with Sartre." For a high priestess of feminism to define herself by her relationship with a man may seem odd. But there are many contradictions between De Beauvoir's life and works.
Simone de Beauvoir's writing, especially Le Deuxime Sexe, published in 1949, influenced generations of young women all over the world. The celebrated first sentence of the second part - "On ne naît pas femme on le devient" (Women are made, not born) is regarded as one of the starting points of modern, radical, feminist thought.
Women's self-image femininity itself is something imposed by a male-constructed civilisation, Beauvoir said. There is no such thing as the innately "feminine". She was not the first to make such an argument but the first to back it up with lengthy (too lengthy?) historical and social and analysis and examples.
The book can be difficult to read today because it expends so many words to make abstract links between feminism and Sartre's theory of existentialism, or the utter moral freedom of the individual.
The book was banned by the Vatican, partly because of its explicit passages on the functions of the female body and descriptions of lesbian sex. Beauvoir also antagonised the church and the existentialist writer Albert Camus by linking the "subordinate" role of mothers, wives and prostitutes in one single, sweeping passage.
The common image of Beauvoir as a haughty, cold, arrogant woman, who lived in the abstract world of the mind has been shattered by a couple of the new books on her life and work. She may not have lived with, or often slept with, Sartre but she did have two long, passionate love affairs with younger men the film director Claude Lanzmann and the American author Nelson Algren.
Lanzmann was roundly booed by radical feminists when he a man dared to make the oration at her funeral. "I never had the feeling that I was living with an icon," he said this week. "She was the least austere of women. Funny, full of fun. She was a real woman, an out-and-out woman."
Beauvoir's letters to Algren, often decorated with lip-stick kisses, make her sound not like a feminist high priestess, but more of a love-struck schoolgirl. "I will be good. I will do the washing-up. I will; sweep up ... I will never do anything you don't want me to do." This is self-mocking but, all the same, shatters the image of the cerebral, uptight blue-stocking writer and thinker.
Even a willingness to play at girliness, or femininity, seems to jar with the main argument of Le DeuximeSexe: that there are no special female qualities; to be free, a woman must act and think like a man. She "prides herself on thinking, taking action, working, creating, on the same terms as men; instead of seeking to disparage them, she declares herself their equal."
This approach remains highly controversial even anathema to some feminists. Antoinette Fouque, literary critic, magazine publisher and co-founder of the Mouvement de Libration des Femmes, finds many of Beauvoir's arguments self-defeating. How can women be against motherhood? Why should women be envious of male qualities and dismiss female ones?
"Her hatred of motherhood and her haughty comments on lesbians, are everything that we now reject," she said. "If being a feminist is to want to be a 'man like any other', as Beauvoir did, then I am definitely not a feminist."
What do younger French women make of Beauvoir? Fanny Mounichy, 21, a masters student in communication at the Sorbonne, says that she feels the game has moved on: women are no longer truly a "second sex" in France but the fight still has to be won in many other parts of the world.
To make radical feminist arguments in France today "indicates that you still feel that you are a victim," she says. "You still feel inferior. Women should still read Le Deuxime Sexe but in a different way to before ... The book still has an important symbolic function in terms of its ideas that we (as women) are not inferior to anyone in any situation. You have to acquire a positive way of thinking you have to believe yourself that you are not inferior. This is especially so in the workplace."
Florence Montreynaud, 59, a historian and feminist author, is the writer of a successful book on different male and female attitudes to love, C'est quoi aimer? She says that she and successive generations of French women owe a great debt to Simone de Beauvoir. However, Le Deuxime Sexe is also, she says, a poorly written book in places; "nowhere near as subtle or humorous as Virginia Woolf's works on the same subject".
All the same, the book had an enormous impact on the women's movement, throughout the world, but especially in France, where women were not given the vote until 1945.
Mme Montreynaud remains, however, puzzled and sometimes even repelled by some of the aspects of Simone de Beauvoir's private life.
"When we discover that Beauvoir used to provide 'fresh meat' for Sartre, in other words young virgin women, what can you say? When you see that the young Beauvoir was suspended from her job as a teacher for a year for seducing her pupils, what can you say?" she says.
"They may have felt themselves somehow too elevated , too important, to be subject to normal moral codes. But we cannot accept that, not if they were hurting others, and clearly they often were. Their behaviour was sometimes appalling, disgusting.
"On the other hand, I believe that their relationship may have been odd he was so ugly and she was so beautiful but it was entirely sincere. It was a relationship of minds.
"They may not have lived together but they loved each other in a way that men and women who do live together find very hard to sustain. I think that they entirely realised that. I think that they decided to live apart, so as to preserve their love."
Men and women, in other words, are doomed to fascinate, then disappoint and finally annoy one another. Sartre once wrote: "Hell is other people". He, and Beauvoir, might also have written: "Hell but also heaven is the opposite sex."
Additional reporting by Emily Murphy