The Lunar Feminine Principle stands as one of the most extensively theorized and symbolically loaded concepts in the depth-psychology corpus. Ranging from Jung’s alchemical investigations through Neumann’s structural archetypology, Edinger’s exegetical scholarship, Moore’s Ficinian imaginal psychology, and Greene and Sasportas’s astrological-psychological synthesis, the term designates a transpersonal psychic principle associated with cyclicity, receptivity, matriarchal consciousness, and the mediating function between the personal and the collective unconscious. A central tension runs throughout the literature: whether the Lunar Feminine is primarily a cosmological-ontological principle—the ‘first gateway of heaven,’ universal receptacle, and funnel of transpersonal influence—or a phenomenological-psychological register, the mode by which collective fantasy is individuated and embodied in felt, temporal experience. Neumann locates the moon within a structural opposition to solar-patriarchal consciousness, arguing that the lunar spirit of matriarchy represents the highest form of earthly-material development rather than incorporeal abstraction. Edinger and Jung both stress the moon’s noetic dimension—its etymological kinship with mens, mensis, and mensura—insisting that mind, measure, and time are themselves lunar achievements. Moore, drawing on Ficino, emphasizes the mediating, timing, and embodying function of Luna. Across these positions, the moon is never reducible to a single valence: it is paradoxical, treacherous, numinous, and generative simultaneously.