Within the depth-psychology corpus, ‘lunacy’ is never merely a synonym for madness. The term carries an irreducible etymological weight — its root in Luna — that the literature exploits with precision. Hillman is the dominant voice, conducting an extended argument in Alchemical Psychology that lunacy names a specific psychological moment: the first irruption of lunar, imaginal consciousness into the solar world. For Hillman, lunacy is not pathology but a necessary alchemical stage, the albedo preceding gold, and its misrecognition by Apollonic medicine — which converts moon-moment into psychiatric case — constitutes the central clinical error of modernity. The key tension runs between lunacy as essential soul-making (Hegel’s insanity as purposeful, alchemy’s silver as precondition of conjunction) and lunacy as insanity when captured by the medical model (echoing Szasz). Hillman further insists that lunacy is inherent in the archetypal principle itself — an infirmity of the archetype, not of the individual — so that lunar understanding, not solar cure, is the proper response. Jung’s work provides the mythological substrate (lunar madness, the moon’s own sickness), while lesser voices in the corpus treat adjacent material on mania, psychosis, and pathological literalism without engaging the specific valence Hillman assigns the term. The concordance entry thus maps a concept at the intersection of alchemical symbolism, anti-psychiatric critique, and a poetics of imagination.