Self mastery, as it moves through the depth-psychology corpus, names no single, settled achievement but rather a contested horizon — the aspiration to govern one’s inner life and, by extension, one’s outward conduct. The term carries radically different valences depending on the tradition in which it appears. In the Indic-yogic literature transmitted through Sri Aurobindo and Eknath Easwaran, self mastery is the precondition for spiritual liberation: the conquest of desire, samskara, and ego-identification that permits consciousness to rise toward its divine ground. For Liu I-ming reading the Taoist I Ching, the concept becomes paradoxical — inward autonomy expressed as outward conformity, a self-control that operates precisely through non-display. Plotinus places self-mastery at the ontological boundary where Being gives way to the One: the Principle beyond Being is the very source of freedom and thus, strictly speaking, beyond even self-mastery as ordinarily conceived. In the clinical literature — Horney’s expansive neurotic solutions, Aurobindo’s discipline of equality, Ogden’s somatic-window work — mastery surfaces as both a genuine developmental achievement and a potential defense. Zimmer’s account of Indian political theology complicates matters further: ahimsa, non-violence, is the first step toward a mastery so complete it becomes superpersonal power. The shared thread is the idea that the self that would master itself must first be differentiated from the personality driven by passion, conditioning, and unconscious reflex — making self mastery inseparable from self-knowledge.