Montaigne treated his own mind as the most reliable evidence available

Rather than building arguments from received authorities, Montaigne started from what he could actually observe: his moods, appetites, fears, and inconsistencies. Bakewell shows this was a radical move for his time, when philosophy was expected to derive truth from Scripture, classical texts, or logical systems handed down by experts. Montaigne distrusted all of that machinery, not because he thought it worthless, but because he noticed how often confident theories collapsed under the pressure of real experience. So he made himself the subject and the instrument at once, cataloguing his own contradictions with a candor that unsettled contemporaries used to authors presenting themselves as consistent and wise. The result reads less like philosophy and more like a mind thinking out loud, correcting itself mid-sentence. This self-focus was not vanity; it was method. If you cannot trust grand systems, the only honest data you have is your own lived, changing experience, examined without flattering yourself. Takeaway: rigorous self-observation, done without self-flattery, is itself a form of intellectual discipline.