Out of all the constituents of the human composition — body, breath, sensations, emotions, relationships, name, reputation — only the TERMruling part is properly the "I." The body and the pneuma are borrowed from common matter and returned to it; everything else lies outside "what is up to us" (dichotomy-of-control). Genuine self-identification is with the rational part of the soul, the part capable of forming judgments and granting assent. In Epictetus this is TERMprohairesis ("the choosing will"); in Marcus the same thing is called ἡγεμονικόν, νοῦς, δαίμων.

SVF II 836 (the doctrine of the ἡγεμονικόν as the locus of personhood); III 169 (ὁρμή as a function of the ruling part); Epict. Disc. 1.1.7, 4.5.12 ("you are not flesh, not hair, but prohairesis"); Ench. 1; Disc. 2.5.4–5 ("my lot is to use impressions"). In Marcus: Med. 2.2; 3.6; 4.41 (with the Epictetan "you are a little soul carrying a corpse"); 5.27; 6.32; 7.16; 10.38; 12.3 (one of the clearest versions of the tripartite division). The Platonic precursor: Alcibiades I 130c ("the human being is the soul" — and specifically its rational part).

In 02-02 the doctrine unfolds as a three-step analysis: σαρκία, πνευμάτιον — external material; ἡγεμονικόν — what remains as the "I." The therapeutic move: what a person takes for himself (body, emotions, reputation) is in fact not him; conversely, what he often ignores (the rational instance) is in fact him. In Hadot this is a central moment of the "discipline of assent": correctly qualifying one's own boundaries. See also meditatio-mortis — the practice that draws the same boundary under the sign of finitude — and definitio — the practice that draws it under the sign of physical stripping-down.