In Individuals Insanity Is Rare But

From Beyond Good and Evil (1886), Chapter IV ("Maxims and Interludes"), Aphorism 156. Nietzsche wrote this book during his middle period, aiming to expose the hidden assumptions of conventional morality and philosophy. The aphorism reflects his diagnosis of herd mentality — the way collective belief systems, national identities, and ideological movements can generate mass delusion that no single individual would exhibit. Writing in the wake of German unification and rising nationalism, Nietzsche saw the capacity for group irrationality as one of the defining dangers of modernity, a theme he developed further in On the Genealogy of Morality (1887).