The symbol-forming function occupies a position of foundational importance in the depth-psychological corpus, designating the psyche’s innate capacity to generate symbols that mediate between instinctual drives and conscious life. Jung’s own formulations, elaborated across multiple works, establish the function as simultaneously biological and spiritual: it is the psyche’s means of converting raw libido into culturally and psychologically serviceable forms, the mechanism by which opposites are held in productive tension rather than collapsing into one-sided identification. Von Franz extends and clarifies this, treating the symbol-forming function as the ‘spiritus rector’ of the unconscious—the coordinating principle that brings the parliament of instincts into unified, directed structure, and which she explicitly identifies with the transcendent function as the enabling condition for individuation. Kalsched approaches the concept from a trauma-theory perspective, demonstrating that the symbol-forming function requires adequate relational conditions to operate; when those conditions fail, affect cannot be metabolized into image, and the protective architecture of the self-care system activates in its place. Across these voices, a central tension persists: is the symbol-forming function a natural, quasi-biological endowment, or does it require cultural and relational scaffolding to become operative? The answer the corpus returns is both, making the concept a hinge between nature and culture, body and spirit, individual and collective.