Within the depth-psychology corpus, the term ‘incestuous’ operates on at least three distinct registers that the literature holds in productive tension. First, there is the literal-clinical register, in which Freud and the early analysts treat incestuous fixations as etiological anchors for neurosis and the Oedipus complex. Second, and far more elaborately developed in the Jungian tradition, the term functions symbolically: incest designates the libido’s regressive pull toward psychic self-fertilization, a movement that, when understood symbolically rather than literally, becomes the engine of individuation, spiritual transformation, and coniunctio. Jung’s most sustained argument — visible across Symbols of Transformation, the Practice of Psychotherapy, and Psychology and Alchemy — is that the ‘incest prohibition’ is less a social regulation of sexuality than the archetypal pressure that separates consciousness from unconscious participation mystique, thereby constituting the self-conscious individual. Third, post-Jungians such as Samuels, Stein, and von Franz develop a relational reading in which the incest impulse and the incest taboo are equally natural, each performing a structural function in the development of consciousness, love, and generational identity. The alchemical literature adds a further dimension: the incestuous union of mother and son, or sibling with sibling, is recast as a cosmogonic necessity — not moral transgression but the paradoxical prerequisite for transformation. Tension persists between the Freudian causal reading (incestuous desire as primary) and the Jungian energic reading (regression to the incestuous as secondary and purposive).