The number seven occupies a position of extraordinary density within the depth-psychology corpus, appearing not as mere arithmetical curiosity but as a structural constant of psychic and cosmological order. Jung locates seven at the penultimate stage of illumination — the threshold before the eighth, which represents completed totality — a formulation elaborated by von Franz through alchemical, planetary, and biblical registers. In the alchemical tradition she surveys, seven governs the number of parables in the Aurora Consurgens, the seven planetary metals, the seven stages of the opus, and the step from differentiation to integration that precedes the octave of wholeness. Edinger reinforces this by tracing the planetary ladder of antiquity, where seven heavens separate earth from the fixed stars, making seven synonymous with the initiation process itself. Hamaker-Zondag introduces the compositional paradox: seven as three-plus-four, uniting dynamic process with material form, while noting its ancient ambiguity as both catastrophic (Babylonian) and sacred (Judaeo-Christian). Evans-Wentz grounds the same periodicity in natural law — chemical series, sound, colour — underwriting the forty-nine-day Bardo structure. Von Franz further demonstrates that when the step from three to four proves too demanding, the unconscious doubles the numbers and the problematic transition appears as the movement from seven to eight. Across these authors, seven consistently figures as the number of evolution, development, and initiatory passage — never the terminus, always the threshold.