Writing had got Montaigne through his "mad reveries" crisis;  it now taught him to look at the world more closely, and increasingly gave him the habit of describing inward sensations and social encounters with precision.  He quoted Pliny on the idea of attending to such elusive fragments:  "Each man is a good education to himself, provided he has the capacity to spy on himself from close up."   As Montaigne the man when about his daily life on the estate, Montaigne the writer walked close behind him, spying and taking notes.

Sarah Bakewell,  How To Live—Or—A Life Of Montaigne: In One Question And Twenty Attempts At An Answer