Donatien Alphonse Francois, Marquis de Sade, was born in Paris in 1740, into an ancient Provencal family which claimed descent not only from Laure de Noves, the 13th-century model for the Laura of Petrarch's sonnets, but also from one of the three Magi. The family made its money from the textile trade, and owned a number of estates and castles in the Vaucluse region of Provence, including the great chateau of La Coste, which the Marquis was to make his principal home. De Sade's father was a diplomat and one of the more infamous rakes of Louis XV's reign. He had a deep aversion to his son, who from early adulthood returned the compliment by far outstripping his father in debauchery; although de Sade inherited the title of Comte when his father died, he preferred to be known as Marquis, as a way of spitting in the face of the old man's ghost. De Sade was also unlucky in his mother, a cold and remote woman who, once she had delivered him, seems almost to have forgotten the existence of her son. Of far more influence on the young de Sade were his many doting aunts and, in particular, his uncle, the Abbe de Sade. This worldly cleric, nicknamed the "sybarite of Saumane", friend of Voltaire and a social luminary in Paris and Avignon, lived the life of a voluptuary within the medieval fortifications of his chateau in Provence, maintaining erotic relations with a large number of women from all classes. It was under the abbe's tutelage that de Sade passed much of his youth. If ever a young man was destined for a life of disorder and sexual excess, it was Donatien de Sade.
The family's fortunes fell sharply when de Sade pere, the unapologetically bisexual Comte, having already forged some unwise alliances among the powerful at court, was arrested by the vice squad for making an indecent approach to a young man in the Tuileries Gardens. It is probable that the old boy's downfall was more the doing of his court enemies than the result of society's moral outrage at his actions. At the highest levels of society, Regency France was one long night-and-day orgy. As the regent's mother remarked, "I'm amazed that France is not totally drowned, like Sodom and Gomorrah." It was within this morally bankrupt world that the Marquis de Sade devised his depravities, real and imagined, and against the hypocrisy of which he rebelled.
In the matter of de Sade the rebel, however, a certain scepticism must be applied. A recent biographer described her subject as "the consummate survival artist". For instance, when the Revolution came, de Sade threw himself into it with characteristic enthusiasm - all that cruelty, that blood, those weeping women! - while remaining at heart a feudal lord, contemptuous both of the mob and of the "crowd of leeches", as he called them, who had infested the court of Versailles. Yet neither his noble blood nor his revolutionary fervour prevented Citizen Sade, in 1790, from joining the bourgeois Society of Authors and declaring himself the professional writer he had always wanted to be.
In 1755, at the age of 15, de Sade, a lieutenant in the King's light cavalry, had been sent into battle in the Seven Years' War. He was 22 when he was honourably discharged. The document releasing him from the army described him as "deranged, but extremely courageous". Although "deranged" refers to his dissolute habits, the characterisation is admirably concise. After some years of riotous and frequently scandalous adventures in Parisian society, he was married off to Renee-Pelagie de Montreuil, daughter of a wealthy Paris judge. Pelagie was spirited, plain and capable, and on more than one occasion was to prove her spouse's saviour. In the annals of wifely loyalty Pelagie de Sade holds a high and honoured place.
De Sade's first serious sexual escapade occurred at Easter, 1768, when he lured a poor young woman, Rose Keller, to a rented cottage at Arceuil, outside Paris, and subjected her to a variety of sexual assaults, including whipping with a cat-o'nine-tails, and delivering cuts to her flesh which he then sealed with molten candlewax. When the girl complained to the police, de Sade was startled: was he not an aristocrat, and were not penniless young women fair game for a great lord such as he? To escape prison he fled to his chateau in Provence, where with the help of his housekeeper and a brood of compliant servants he passed a winter of orgiastic frolics before being captured and sent to the prison fortress of Vincennes.
De Sade's orgies, the most amazing of which were staged, and stage-managed, at La Coste, and which were to send him to jail for some 13 years, were, like his books, masterpieces of stylisation, the object of which was not so much erotic pleasure as the exercise of absolute power. When he was called to account for his behaviour, by the parents of his serving girls and then by the police, he was once again surprised and indignant. He could not see why those in authority should feel compelled to take away his toys. His mother-in-law, Mme de Montreuil, known as La Presidente, was a formidable woman and a relentless foe. At the outset, she was charmed by the noble if wayward de Sade - she may even have lusted after him - and through her husband's contacts in legal circles worked to save the young man from prison. Later, however, when he had consistently refused to bend to her will, she set about getting him imprisoned for life. In the years to 1789, de Sade spent very long stretches behind bars, and was in the Bastille when the Revolution broke out - from his cell window he addressed the mob in the street below, employing as a megaphone a long metal funnel normally used for urinating through into the moat - although he was transferred to the asylum "hospital" at Charenton shortly before the storming of the prison.
After his release, Pelagie, who had supported him through all the long trial of their life together, decided that she wanted no more of him, and sought a divorce. De Sade, who had genuinely loved his wife - their relationship is one of the most mysterious, and affecting, in the history of married life - once again showed his aristocratic coldness by taking up straight away with another woman, Constance Quesnet, who was to be his devoted partner for the rest of his life. Now a writer and a man of some importance in the revolutionary regime, de Sade found himself, no doubt to his amusement, once again a kind of noble. He was elected president of his district, a position of considerable power - not least over his old enemy, Mme la Presidente, now down on her luck - and was called on to deliver the oration at the funeral of the assassinated Jean-Paul Marat. However, in the end the nouveau regime came to find de Sade and his writings as uncongenial as had the ancien regime, and eventually he was locked away in the Charenton asylum, where he died in 1814.
What is de Sade's legacy, other than a handy word that can be used to characterise everything from capital punishment in schools to the unspeakable practices of Fred and Rosemary West? He is more talked about than read. Simone de Beauvoir put it well when she wrote that his "perverse bucolics have the grim austerity of a nudist colony". Justine, his first great succes de scandale, is a mixture of plodding obscenity and pious mock-moralising. His masterpiece is undoubtedly The 120 Days of Sodom, a sort of early modernist novel cataloguing a series of increasingly mechanical perversions interspersed with de Sade's particular brand of cod philosophy. Read from a certain angle, these books can look remarkably like harsh, subversive comedies. Was he, perhaps, not a pornographer at all, but one of the great farceurs? Certainly, his laughter is still clearly to be heard, echoing down the grim stone corridors of history.
The film Quills, starring Geoffrey Rush as the Marquis De Sade, opened yesterday. Sade, starring Daniel Auteuil, will open later this year. The most recent biography, At Home With the Marquis De Sade by Francine du Plessix Gray is published by Pimlico, £15 in UK