Stoic Discipline, treated in the depth-psychology corpus through the overlapping lenses of Pierre Hadot, Epictetus, Marcus Aurelius, Nussbaum, and Inwood, names a tripartite regimen of self-governance whose three axes—discipline of assent (judgment over representational impressions), discipline of desire (alignment with universal Nature and fate), and discipline of action (justice in relation to the human community)—constitute philosophy not as theory but as a lived practice of transformation. Hadot’s reconstruction, particularly in The Inner Citadel and What Is Ancient Philosophy?, argues that this ternary structure is internally necessary: there can be neither more nor fewer than three disciplines because they map onto the three fundamental acts of the soul and the three parts of Stoic philosophy—logic, physics, and ethics. The hēgemonikon, or ruling faculty, stands as the seat from which all three disciplines operate, and the inner citadel it governs is impregnable precisely insofar as the agent maintains sovereignty over assent. Epictetus furnishes the practitioner’s voice: philosophy is preparation for adversity, training for the moment fever or hunger or loss arrives. A tension runs through the corpus between the Stoic ideal of the self-sufficient rational sage and modern psychological accounts of the self as constitutively relational, permeable, and unconscious. Nussbaum presses this tension most acutely, noting that Stoic rationalism—its identification of the divine faculty with practical choice—risks foreclosing the very vulnerability that makes ethical life possible. Inwood, working from early Stoic sources, grounds the discipline in naturalism: virtue is what fulfills human nature, and moral action is inseparable from that teleological structure.