Within the depth-psychology corpus, Sun and Moon function as the primary pair of psychic opposites — irreducible polarities whose dynamic tension organizes both the individual psyche and the symbolic universe of alchemy, mythology, and astrological interpretation. Jung roots the pair in the fundamental structure of consciousness itself: the Sun symbolizes the sorting principle that raises contents above the psychic threshold, while shadow and unconscious correspond to the lunar domain. Von Franz extends this in her alchemical readings, where the coniunctio of Sun and Moon enacts the paradoxical unification of conscious and unconscious conflict, the very goal of the opus. In the astrological tradition, Greene and Sasportas treat the luminaries as the two master significators of selfhood — the Sun as the trajectory of individuation and creative identity, the Moon as the instinctual, embodied, receptive vessel — whose angular relationship (lunation phase) encodes the shape of a life. Rudhyar situates them philosophically within geocentric symbolism as complementary principles of light and periodicity, masculine and feminine, spirit and matter. Across these traditions, tensions persist: whether the pair is primarily cosmological or psychological, whether their union signifies integration or dissolution, and whether lunar priority (nomadic, pre-solar worship) or solar primacy (agricultural, patriarchal) represents the older stratum of human experience.