One of the greatest game-changers in French literature was the Essais of Michel de Montaigne, which first appeared in 1580. The title itself was a linguistic innovation, announcing the birth of a new literary form in which serious topics would be dealt with in a style that was tentative, ironic and anecdotal, rather than rigorous, serious and systematic. Thanks to Montaigne, intellectual argument would be liberated from the chapter and verse of the scholar’s treatise and the repetitive rote of lecturers in schools. It would become indistinguishable from the spontaneous conversation of civilised companions sauntering round town or galloping over the countryside or sitting at a well-furnished table.

The content of the Essais followed the form: a celebration of ‘diversity of judgement’, as Montaigne put it, by means of ‘fooling and fantastication’. All of us, he said, ‘are, I know not how, double in ourselves, which is the cause that what we believe we do not believe, and cannot separate ourselves from what we condemn’. For him, doubt and hesitation were the mark of true wisdom, and resolute certainty was ‘for lunatics’.

The Essais were a game-changer for English literature too. Francis Bacon tried to match their conscious nonchalance in his own Essays in 1597, and in 1603 they were ‘done into English’ by John Florio to enormous effect. Florio’s translation was a linguistic revolution in itself: it is the source of almost two hundred new words in the Oxford English Dictionary, from ‘abecedarian’ and ‘amusing’ to ‘sophisticated’ and ‘unfoolish’. It also opened a new vista of fantasy, exoticism and ruminative indirection, from Shakespeare’s Tempest to Robert Burton’s The Anatomy of Melancholy and Thomas Browne’s Religio Medici. But its most important legacy lay in a different quarter. Montaigne pioneered a new use of the first person, deploying it not for boasting and bragging but for humorous self-deprecation. ‘Reader, loe-here a well-meaning Booke’, as he put it an introductory address ‘to the reader’, as translated by Florio. ‘In contriving the same, I have proposed unto my selfe no other than a familiar and private end … for it is myselfe I pourtray. My imperfections shall therein be read to the life … it is then no reason thou shouldest employ thy time about so frivolous and vaine a subject.’ Ever since then, English literature has been swamped with the progeny of Montaigne: lovable but unreliable characters, chuckling, twinkly eyed, bumbling, avuncular and corpulent, from Tristram Shandy to Mr Pickwick and Rumpole of the Bailey.

For those who find this persona rather wearisome, Philippe Desan brings good news: Montaigne, who launched the whole cult of blokeish bonhomie, was not so much a cheerful old codger as a ruthless social climber. He was born Michel Eyquem in 1533 to a family of Bordeaux tradesmen who, having made a fortune out of fish, now aspired to aristocratic distinction. They dabbled in city politics and bought a small chateau in a Dordogne village called Montaigne, adding a wall and towers to make it look like a fortified castle. But their real hopes rested on the little boy, who was put under a tutor at the age of three and required to speak nothing but Latin. He was then sent to an expensive boarding school and to various universities, in the hope that by practising law he would be able to infiltrate the nobility. He spent twelve laborious years producing briefs and legal memoranda for the appeals courts of Bordeaux, and sometimes carried messages to the royal palaces of Catherine de’ Medici and Charles IX. But fame and advancement eluded him, and by the time of his father’s death, in 1568, his career seemed to have stalled.

In his late thirties, Montaigne decided to move back to the family chateau, building a library in a tower where he could relax in the company of his books. According to the standard story, he was renouncing the busy world in the hope of achieving inner philosophical peace. According to Desan, however, he was simply trying to buttress his claims to nobility by covering his tracks as a jobbing lawyer and reinventing himself as a humanist man of letters. While acknowledging the charms and insights that have appealed to generations of doting readers, Desan insists that, as far as Montaigne was concerned, the Essais were intended to demonstrate that he possessed the cultural attributes appropriate to the scion of a noble family. Hence the carefully composed title page, which focuses attention not on the work but on its author – not Michel Eyquem, but ‘messire Michel, Seigneur de Montaigne, Chevalier de l’ordre du Roy, et Gentil-homme ordinaire de sa chambre’. He had sloughed off his family surname in order to present himself as part of the landed nobility. He was, in his way, a prototype of Molière’s bourgeois gentilhomme.

Desan makes his case by exploring in great detail the legal, political, religious and literary institutions of 16th-century France, and showing how Montaigne positioned himself within them. He cannot quite explain why Charles IX chose to appoint him to the exalted Ordre de St Michel in 1571, but he evokes the contemptuous reaction of well-established courtiers who concluded that honour inflation was eroding the value of ancient titles. And he shows that while the philosophical chapters of the Essais served to vindicate Montaigne as a Renaissance scholar, those on war, horsemanship, duelling and courtly protocol were meant to prove his suitability for personal service to the state. The famously charming address ‘to the reader’ was, according to Desan, meant specifically for Henry III (who succeeded Charles IX in 1574). Montaigne contrived to present a personal copy to the king, and when he heard that it had met with approval, he jumped to the conclusion that he had a chance of being appointed ambassador to the Holy See. In the event he was passed over, even though he had travelled to Rome to hold himself in readiness. But by way of compensation, Henry had him appointed mayor of Bordeaux, a post that he would hold until 1585. By that time he was secure in his title as Seigneur de Montaigne, and he started to rework the Essais for a new edition, which appeared in 1588, and then for another that he was still working on when he died, in 1592, at the age of fifty-nine. In these later versions he presented himself not as a courtier eager to serve the state, but as a mellow scholar who had never cared for worldly honour – thus painting the self-portrait that has governed the reception of his writings ever since.

Desan’s Montaigne was published in French in 2014, and is written in the manner of an eminent maître who feels no obligation to adapt himself to the needs of the common reader. His narrative is labyrinthine and his prose copious; his translators have, so far as I can tell, faithfully reproduced every redundancy and repetition of the original. On the other hand, the title has undergone a curious transmogrification: what was ‘une biographie politique’ is offered to the English-reading public as simply ‘A Life’, even though a reader without much prior knowledge of Montaigne and 16th-century France will be unable to make head or tail of it. It is a wonderful book in its way, but those who are in a position to appreciate it will probably prefer to read it in the original rather than in translation. Either way, Montaigne will never look quite the same.