The 6th of Sarah Bakewell's 7 part series on Montaigne, in The Guardian:
In 1580, just after publishing the first edition of his Essays, Montaigne had an audience with Henri III in Paris. Henri said he liked the book very much, to which Montaigne reportedly replied, “Sir, then your majesty must like me”. For, as he always maintained, he and his essays were one. “I have no more made my book than my book has made me”, he wrote, “it is a book consubstantial with its author”.
And this was just the beginning. By the time of its publication, he and his text had been growing together for eight years; now he would add material for 12 more, probably until the year of his death, 1592. More editions came out, and he left annotated copies for a vast posthumous one. He seems to have amazed even himself: “Who does not see that I have taken a road along which I shall go, without stopping and without effort, as long as there is ink and paper in the world?”
All this writing and tinkering rarely took the form of changing anything, or crossing out old versions. When Montaigne thought of some new angle on a question, he usually inserted it without further adjustment, even if this produced contradictions. He preferred not to repent of choices he had made either in literature or in life. His past selves each had their own voice, even if the new Montaigne no longer understood them. Thus, within a paragraph or two of the Essays, we may meet Montaigne as a young man, then as an old man with one foot in the grave, and then again as a middle-aged mayor bowed down by responsibilities. We may listen to him complaining of impotence; a moment later we see him young and lusty and bent on seduction. “I do not portray being”, he wrote; “I portray passing. Not the passing from one age to another … but from day to day, from minute to minute.” His let his thoughts lie where they fell.
Why did he do it? What, really, was he trying to achieve by “essaying” his life for so long? His love of communication had something to do with it. But writing also helped him to live a better life: to become more truly, and more thoughtfully, himself.