Darkness occupies a position of remarkable semantic density across the depth-psychology corpus, functioning simultaneously as ontological category, psychological condition, initiatory threshold, and metaphysical principle. Jung and his interpreters treat darkness neither as mere absence of light nor as simple moral privation, but as a constitutive pole of psychic wholeness whose confrontation is prerequisite to individuation. The ‘sight of its darkness is itself an illumination,’ Jung declares in the Mysterium Coniunctionis, locating in shadow-recognition the very mechanism of expanding consciousness. Hillman complicates this Jungian integrationism by insisting the unconscious is dark for two reasons simultaneously: the Freudian repressed and a second, irreducible darkness that exceeds what reason can metabolize. Corbin’s Iranian Sufi materials introduce a crucial tripartite structure — the luminous Night of superconsciousness, the intermediate day of consciousness, and the dark Night of the subconscious — distinguishing the divine Darkness of the Cloud of Unknowing from the demonic darkness that imprisons light-particles. The Taoist I Ching’s hexagram Darkness (Kan) offers yet another register: obscurity as a condition of yin’s dominance over yang, traversable through proper timing and authentic self-awareness. Across Gnostic, alchemical, Greek tragic, and Tantric sources, darkness emerges as the ground from which knowing becomes possible, a necessary counterpart — not enemy — of illumination.