The only four-step demonstration in the corpus. The passage is built as a sorites, unusually explicit for Marcus: (1) no φύσις is inferior to τέχνη, since the arts imitate natures; (2) therefore the most complete of natures will not fall short of the ingenuity of craft; (3) every art makes the worse for the sake of the better; (4) therefore the common nature does so too. From the fourth step δικαιοσύνη is derived.

The opening premise is a quotation. ʽMOTIFΟὐκ ἔστι χείρων οὐδεμία φύσις τέχνηςʼ is given in quotation marks as someone else's saying, and Marcus at once grounds it: καὶ γὰρ αἱ τέχναι τὰς φύσεις μιμοῦνται. The argument from imitation: a copy is never better than its model. From here the road runs straight to the image of MOTIFnature the craftsman — with the difference that here the workshop is proved rather than described.

The word the third step rests on. τῶν κρειττόνων ἕνεκεν τὰ χείρω ποιοῦσιν — "they make the worse for the sake of the better." This is the school's definition of purposiveness: in a craft the subordinate exists for the sake of the principal (the blank for the sake of the finished thing). Transferred to κοινὴ φύσις, it just is Stoic DOGMAprovidence — not attention to particulars but hierarchy for the sake of the whole.

The unexpected conclusion: justice out of physics. ἔνθεν μὲν γένεσις TERMδικαιοσύνης — "hence the birth of justice." The move deserves noting: justice is neither posited as a duty nor derived from a contract, but obtained as a consequence of cosmology. If the whole is so ordered that the lower serves the higher, then the rational part is bound to stand toward the whole accordingly; and hence too the primacy of justice: ἀπὸ δὲ ταύτης αἱ λοιπαὶ TERMἀρεταὶ ὑφίστανται, "from it the remaining virtues have their standing." Cf. 11.1, where the same thesis appears not as an inference but as an identification: right reason and the reason of justice differ in nothing.

Three ways of losing justice. The close lists the conditions of failure: διαφερώμεθα πρὸς τὰ μέσα — "if we are exercised about the middle things" (τὰ μέσα is the school's synonym for the indifferent; the term ἀδιάφορα itself does not occur, and Long inserts a bracketed gloss); and three adjectives in -τικός: εὐεξαπάτητοι ("easily deceived"), προπτωτικοί ("headlong," from προπίπτω, to fall forward), μεταπτωτικοί ("shifting," literally "falling across"). The first concerns desire, the other three assent: justice rests not on good intention but on soberness of judgement. The governing discipline is assent, the sustaining one action.