The passage as an inference from two premises. A rare case in Marcus of an explicitly stated logical form: πρῶτον κείσθω… ἔπειτα — "first let this be laid down… next." Two premises: (1) DOGMAI am a part of the Whole, governed by nature; (2) DOGMAI stand "in a way related as one's own" (ἔχω πως οἰκείως) to the parts of my own kind — the root οἰκει- itself, that is, the school term oikeiōsis. From the first follows one's relation to what happens, from the second one's relation to people, and from both together the conclusion about the tenor of life.

The disjunction set aside. The opening is «εἴτε ἄτομοι εἴτε φύσις». At 9.39 Marcus works both branches out; here he does not even separate them: whatever the physics, the premises are laid down all the same. This is not carelessness but a demonstration that the practical conclusion does not depend on the outcome of the cosmological dispute. Note too the asymmetry: the premise is already framed as «ὑπὸ φύσεως διοικουμένου» — the atomist branch is silently left behind.

The strong form of the theodicy. The argument against discontent: οὐδὲν βλαβερὸν τῷ μέρει ὃ τῷ ὅλῳ συμφέρει — "nothing that benefits the Whole is harmful to the part." And why can the Whole not be to its own harm? Because no nature contains anything unprofitable to itself, and the nature of the cosmos has in addition (προσειληφυίας) that no external cause can compel it. This is the strongest available formulation: not "the Whole is good," but — the Whole has no outside, and there is nowhere for compulsion to come from. Cf. 6.45; 5.8.

Two consequences and one conclusion. From the first premise: DOGMAεὐαρεστήσω παντὶ τῷ ἀποβαίνοντι, "I shall be well pleased with all that comes about." From the second: οὐδὲν πράξω ἀκοινώνητον, "I shall do nothing unsocial," and every TERMὁρμή shall be directed toward the κοινῇ συμφέρον (cf. 7.13). The conclusion is given as a necessity, not a hope: ἀνάγκη τὸν βίον TERMεὐροεῖν — "life must flow smoothly." εὔροια is the school's definition of happiness (εὔρους βίος), and Marcus says that it follows from the two premises with logical force.

The citizen as the figure. The close draws both halves into a single image: DOGMAthe life of a citizen who proceeds "through acts that profit his fellow citizens" (action) and "welcomes (ἀσπαζομένου) whatever the city assigns him" (desire). Both disciplines in one person — which is why the passage resists assignment to either: desire is taken as governing, since the inference begins there, but the discipline of action that carries it is its equal.