The canonical telos (final end) of Stoic ethics, transmitted by the formula τὸ ὁμολογουμένως τῇ φύσει ζῆν — "to live in agreement with nature." The Stoic telos-formula was developed in stages:

• Zeno (SVF I 179, cited Stob. Ecl. II 75 W): τέλος εἶναι τὸ ὁμολογουμένως ζῆν — "the end is to live in agreement [with oneself]," that is, in concord with one's own single λόγος, in no contradiction with itself.
• Cleanthes (SVF I 552) adds a qualification: τὸ ὁμολογουμένως τῇ φύσει ζῆν, "according to nature"; he specifies what one is to agree with.
• Chrysippus (SVF III 4–16) unfolds "nature" as twofold: the nature of the whole (κοινὴ φύσις) and the nature of the human being as a rational creature (ἰδία φύσις). To live in accordance with nature means simultaneously (a) to obey the rational order of the cosmos and (b) to realise one's own rational-social essence.

The double "nature" is not self-contradictory, because human nature is "to be a part of cosmic nature": an individual logos is the Logos of the whole expressed at a local point. To act κατὰ φύσιν is therefore at once to do what is one's own (one's human, one's rational task) and to do what the cosmos "wants" (to fulfil one's role in the common order).

SVF I 179 (Zeno), 552 (Cleanthes); III 4–16 (Chrysippus); the classical formulations: DL VII 87–89; Stob. Ecl. II 75–76, 86 W; Cic. De fin. III 26, 31. In Marcus the theme is constant: Med. 2.9; 2.16 (how τὸ κατὰ φύσιν lives); 04-51 (the short road = the road according to nature); 05-01 (at dawn I rise to a "human's work," by nature); 05-03; 05-04; 05-09; 05-15 (to live by human nature — not to demand the non-human); 05-25 (I have what κοινὴ φύσις wills, I do what ἐμὴ φύσις wills); 05-29; 06-33 (the toil proper to a human is not against nature, and so not an evil); 06-40 (to live by nature's inner will → all κατὰ νοῦν); 06-58 (no one hinders living by the reason of one's own nature; nothing is against the common nature); 07-11 (the axiom of identity — the same act κατὰ φύσιν and κατὰ λόγον); 07-20 (the one worry — an act against the human κατασκευή: wrong thing, wrong way, or wrong time); 07-24 (the scowl λίαν παρὰ φύσιν — and therefore against reason); 6.42; 07-55; 07-56 (the remainder of life — a surplus, yet lived by nature); 07-74 (benefit = πρᾶξις κατὰ φύσιν — to do good is the rational being's nature); 08-01 (seek the good life not in externals but in fulfilling one's nature's requirements); 08-05 (all is according to the nature of the Whole; do what man's nature requires); 08-07 (a nature "fares well," εὐοδεῖ, by fulfilling three conditions); 08-12 (ὃ κατὰ φύσιν ἑκάστῳ — what accords with one's nature is its own and more agreeable); 08-19 (each thing has its πρός τι; a human's end is not pleasure); 08-26 (joy is to do τὰ ἴδια ἀνθρώπου, one's own by nature); 08-46 (to each happens only what is customary and natural — εἴωθε καὶ πέφυκε); 08-50 (accept a thing's nature — the bitter cucumber, the brambles — without a "why"); 08-52 (not to know πρὸς ὅ τι πέφυκας — for what you exist — is not to know who you are); 09-01 ("the one who wishes to follow nature" must hold evenly to what she uses equally — else impiety); 09-03 (to live and die by nature — death as her "operation"); 09-29 (ποίησον ὃ νῦν ἡ φύσις ἀπαιτεῖ — do what nature now demands; the modest work of philosophy); 09-42 (having done something κατὰ φύσιν τὴν σήν you already "have what is your own" — no wage is sought beyond the act); 10-02 (the three natures and the rule of subordination: the lower is satisfied so long as it does not spoil the higher); 10.6; 10-08 (a fig-tree does the work of a fig-tree, a dog of a dog, a man of a man; likeness to god just is the discharge of one's own nature); 10-11 (εὐθεῖαν περαίνειν διὰ τοῦ νόμου καὶ ἕπεσθαι τῷ θεῷ — the straight line through the law just is the following of God); 10-15 (let people examine a man κατὰ φύσιν ζῶντα); 10-36 (ἓν γὰρ καὶ τοῦτο τῶν κατὰ φύσιν — the formula applied to the hardest case: the severing from those nature joined you to); 11-05 (the two branches of θεωρήματα — on the nature of the Whole and on the constitution proper to a human being — are the τέλος-formula in compressed form); 11-06 (ταῦτα οὕτως πέφυκε γίνεσθαι — what tragedy reminds us of is precisely that this is how things naturally come about); 11.16; 12-01. Seneca's Latin transposition of the formula: Ep. 5.4; Ep. 41.9 ("secundum naturam vivere"). Cf. 11-16 (a fork instead of a prohibition: if κατὰ φύσιν, rejoice; if παρὰ φύσιν, seek what is your own, "even if it brings no repute") and 11-20 (nothing βίαιον is laid upon the rational part, only τὰ κατὰ φύσιν — and still it is carried the opposite way); 11-34 (the redefinition of δύσφημον: nothing that signifies some work of nature is a word of ill omen — else "the ears of corn are reaped" would be one too). And 12-11 (τὸ ἑξῆς τῇ φύσει — three verbless words that Long does not render at all and Rogovin expands into an explanation). And 12-31 (once all the faculties are set aside, what is left is τελευταῖον — τὸ ἕπεσθαι τῷ λόγῳ καὶ τῷ θεῷ); 12-32 (the formula split along the two natures: ποιεῖν as one's own leads, πάσχειν as the common one brings). In Books I–IV: 02-17 (κατὰ φύσιν), 03-04 (τῶν ὁμολογουμένως τῇ φύσει βιούντων — theirs is the only opinion worth valuing), 03-09 and 03-16, where the formula is given as following the gods (ἡ τοῖς θεοῖς ἀκολουθία, ἑπόμενον θεῷ).

In 02-09 the telos-formula appears not as a declaration but as the structure of a meditation: five points "always to be remembered" (μεμνῆσθαι), and these are the unfolded content of "to live according to TERMnature":

1. the nature of the whole — what κοινὴ φύσις is;
2. my own nature — what ἰδία φύσις is;
3. how the first relates to the second — the structural correspondence;
4. of what part of what whole I am — the part within the whole;
5. that no one can prevent me from acting «τὰ ἀκόλουθα τῇ φύσει» — the freedom to act according to nature is always up to us.

The final point is the Stoic intuition of the inalienability of moral freedom: external circumstances can deprive me of a thousand things, but not of the capacity to act κατὰ φύσιν, because that capacity is a structural property of the ruling part, not removable from outside. See the self-sufficiency of virtue: this doctrine and "to live according to nature" are two sides of one coin — virtue is sufficient because it is "to live according to nature," and this is entirely up to us.