Around 1576 a retired magistrate from near Bordeaux had a medal engraved with his age and two mottoes in the spirit of the ancient Sceptics, the school that answered every argument with an equal and opposite one. The first was a Greek word for holding back one's judgement. The second, in French, asked what he knew. France had been at war with itself over religion since 1562, Catholics against Protestants, and each side was sure enough of God's will to kill for it. Michel de Montaigne spent the rest of his life asking how much any human being is entitled to be sure of.
He came to the question as a lawyer. By 1557 he sat as a judge, first in a tax court at Périgueux and then in the Parlement of Bordeaux, the region's high court of appeal. There he formed an intimate friendship with Étienne de La Boétie, a humanist poet two years older, which lasted until La Boétie's death in August 1563. Montaigne later wrote the essay "Of Friendship" about him. In 1570 he sold his seat. On his thirty-eighth birthday, 28 February 1571, he withdrew to a library in a tower on his estate, and within a year he had begun to write.
The book he wrote there, the Essays (Essais), takes one ordinary man — himself — as its subject. Its title comes from the French verb essayer, to try or to test, and each chapter tests his judgement on something: custom, death, friendship, cruelty, God. He said he studied himself more than any other subject, and what he found was a judgement pushed about by habit, health and mood. The conclusion he drew was practical: he offered his opinions as what he believed, not as what others should believe, and he ranked cruelty as the worst of the vices. He argued that burning an accused witch alive set too high a price on a guess. In "Of Cannibals" he described three Tupinambá men from Brazil who were at Rouen in 1562, where the twelve-year-old king, Charles IX, talked with them. They were puzzled that armed, bearded men obeyed a boy, and that some Frenchmen begged at the doors of others who were gorged.
His scepticism is argued most fully in the longest chapter, "Apology for Raymond Sebond". At his father's request he had translated the Natural Theology of Sebond, a Catalan theologian who set out to prove the Christian faith by reason, and published it in 1569. The "Apology" defends Sebond by taking apart the confidence of reason itself. Scholars disagree about where that leaves his religion. Richard Popkin, the historian of scepticism, read it as fideism: reason cannot prove the faith, so faith must stand on its own. Others point to the places where Montaigne holds firm convictions and doubt that "sceptic" fits him at all.
He did not stay in the tower. Elected mayor of Bordeaux in 1581 while he was travelling in Italy, he was re-elected in 1583 and served until 1585. As mayor he stayed loyal to the Catholic king, Henri III, while keeping on good terms with the Protestant leader, Henri of Navarre. In 1588 the Catholic League, the militant Catholic party, drove Henri III out of Paris, and a duke loyal to the League had Montaigne put in the Bastille. He was released the same day. He spent his last years writing additions in the margins of his copy of the 1588 edition, lengthening the book by about a third, and died at his château in September 1592.
Descartes answered Montaigne's doubts in his Discourse on Method (1637), borrowing from the Essays without naming their author. Antoine Arnauld and Pierre Nicole, the logicians of Port-Royal Abbey, condemned him as scandalous. In 1676 the Catholic Church put the Essays on the Index of Prohibited Books, and his influence in France faded for fifty years. In the late twentieth century the political theorist Judith Shklar called him the first modern liberal, because he put cruelty first among the vices.