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); 4.51; 5.3; 5.9; 6.42; 7.55; 10.6; 11.16; 12.1. Seneca's Latin transposition of the formula: Ep. 5.4; Ep. 41.9 ("secundum naturam vivere").

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.