Reason, which fifty times for one does err,
Reason, an ignis fatuus of the mind.

These lines are from John Wilmot, Earl of Rochester’s Restoration satire “A Satyr Against Reason and Mankind” (c. 1670s), a poem that attacks the pretensions of “right reason” and the fashionable rationalism of his age. Writing as a court wit in the libertine milieu of Charles II’s court, Rochester adopts a deliberately provocative stance: he contrasts fallible human “reason” with instinct, appetite, and experience, arguing that what people call reason often serves as a self-justifying mask for pride and error. The poem circulated in manuscript and was later printed posthumously, becoming one of Rochester’s best-known and most controversial works.

Rochester portrays reason not as a reliable guide but as a deceptive will-o’-the-wisp (“ignis fatuus”) that misleads the mind far more often than it enlightens it. The hyperbole “fifty times for one” underscores his skepticism about human rationality in practice: people invoke reason while actually rationalizing desire, vanity, or social convention. The image suggests that reason can lure us into intellectual swamps—false systems, sophistries, and moral posturing—rather than toward truth. In the poem’s broader argument, this is less a rejection of thinking itself than a satiric exposure of reason’s corruption by self-interest and the limits of human knowledge.