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"); 05-10; 05-21 (honour the mightiest in the cosmos — and what is akin to it in yourself); 05-26; 05-27; 06-16; 6.32; 7.16; 07-55 (the νοερὰ κίνησις "circumscribes itself," means to hold first place over sense and appetite); 07-59 (ἔνδον ἡ πηγὴ τοῦ ἀγαθοῦ — the good is in the ruling part itself, one need only dig); 07-67 (περιορίζειν ἑαυτόν — to circumscribe yourself and keep your own in your power); 07-72 (the rational-social faculty judges below itself all that is neither rational nor social); 08-03 (the philosophers' ruling faculties are the same as themselves — τὰ ἡγεμονικὰ ἦν αὐτῶν ταὐτά); 08-16 (a change of mind is σὴ ἐνέργεια, the ruling part's own act); 08-27 (the body is only the enveloping ἀγγεῖον, a "vessel," not the "I"); 08-28 (no evil ascends into the ruling part from without); 08-40 (τίς αὐτός; — ὁ λόγος: the "self" is reason); 08-43 (joy is ὑγιὲς τὸ ἡγεμονικόν, the health of the ruling part); 08-48 (the ruling part, coiled into itself, is an unassailable citadel); 08-51 (the διάνοια stays pure under abuse — like an undefilable spring); 08-56 (each ἡγεμονικόν is a sovereign, holding τὴν ἰδίαν κυρίαν; another's vice does not enter it); 09-07 (ἐφ’ ἑαυτῷ ἔχειν τὸ ἡγεμονικόν — to keep the ruling part in its own power); 09-15 (things "outside the doors" are mute — τὸ ἡγεμονικόν pronounces about them; the "self" is the judging part); 09-26 (contentment with the ἡγεμονικόν doing its own work — "and enough"); 10-24 (ποιῶ and χρῶμαι: the ruling part is not given ready-made — it is manufactured by the use one puts it to); 10-38 (τὸ ἔνδον ἐγκεκρυμμένον, named without a single technical term, and three ascending identifications — speech, life and, "if one must say it," the man); 12-03 (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). And 12-19 (κρεῖττόν τι καὶ δαιμονιώτερον ἔχεις ἐν σαυτῷ — pointed to not by description but by a comparative: that which is above what jerks you about). And 12-33 (ἐν γὰρ τούτῳ τὸ πᾶν ἐστι — not "the chief thing" but everything; and all the rest, on both sides of the dichotomy, is called νεκρὰ καὶ καπνός). In Books I–IV: 04-01 (τὸ ἔνδον κυριεῦον — "the inward ruling thing," named without the technical term).

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.

In 03-03 the doctrine is compressed into a lapidary four-word formula: τὸ μὲν γὰρ νοῦς καὶ δαίμων, τὸ δὲ γῆ καὶ λύθρος — "the one is TERMmind and daimon, the other earth and gore." The body as the ἀγγεῖον (vessel) which the "I" mistakenly serves; death merely lifts that servitude. One of the most concentrated statements of the doctrine in the whole corpus.

In 03-05 the doctrine appears as self-sufficiency: ὀρθὸν εἶναι χρή, οὐχὶ ὀρθούμενον — "one must be upright, not set upright"; and "the god in you" (ὁ ἐν σοὶ θεός) is one's own guardian, needing neither oath nor witness nor the calm that others provide. The self is load-bearing, not propped from outside. Cf. 11-19, where the fourth aberration is recognised by shame: τὸ ἐν σοὶ θειότερον μέρος has "laid itself under" (ὑποκατακλινομένου) the ἀτιμοτέρα καὶ θνητὴ μοῖρα — by the same rare verb that at 11-14 describes servility before other people.