as in 4.22, where he says every impulse should be subject to the claims of justice and keeping our
convictions clear.
Kathêkon (καθῆκον): duty, appropriate action on the path to virtue. Diogenes Laertius says that
Zeno was the first philosopher to use the term as relating to conduct in the sense of being incumbent
upon an actor (Lives of the Eminent Philosophers, “Zeno,” 7.108). Marcus says that every duty in life
is a sum of acts that deserve methodical attention (6.26).
Koinos (κοινός): common, shared in common. As Haines noted, this term and its cognates appear
more than eighty times in Marcus, and it is a very central part of his thinking and ethical orientation.
Community, partnership, fellowship, neighborliness, and cooperation are all heavily emphasized in
terms ranging from κοινωνία (5.16, and “action for the common good in the present moment” in 9.6)
to his own coined word κοινονοημοσύνη, regard for the feelings of others (1.16). In 6.30, Marcus
tells us, “Life is short—the fruit of this life is a good character and acts for the common good.” See
also his morning ritual to remind ourselves that we’ve “been made by nature for the purpose of
working with others” (8.12). A related common term appearing in both Marcus and Epictetus is the
word ἀλλήλων/allêlôn, which stresses how we are made “for each other” or “for one another”
(twenty-six times in Marcus, especially 5.16 and 6.38; and twenty times in Epictetus, notably 2.20).
Kosmos (κόσμος): all-encompassing order, world, universe.
Logos/Logikos (λόγος/λογικός): reason or rational; the ordering principle of the cosmos. Logos
spermatikos (λόγος σπερματικός) is the generative principle of the universe, which creates and takes
back all things (see Marcus 6.24).
Nomos (νόμος): law, custom.
Oiêsis (οἴησις): conceit, self-deception, illusion, arrogant opinion or notion. Epictetus says
(3.14.8) that two things must be rooted out of every human being: self-deception and
mistrust/timidity (apistia). Our conceit, arrogance, and false opinions are what must be removed
(2.17.1), along with passion (pathos). Epictetus sees a movement from preconception (prolêpsis)
through conception (hypolêpsis) to our more firmly formed convictions (katalêpsis), and all can be
subject to error (hamartia). Heraclitus called self-deception “an awful disease” (Diogenes Laertius,
Lives of the Eminent Philosophers, 9.7), and the Stoics offered their practices for overcoming it.
Oikeiôsis (οἰκείωσις): self-ownership, appropriation to the individual’s or species’ needs. There
is only one instance of this noun in Epictetus (Discourses 1.19.15), which pertains to self-
preservation, although it appears in a discussion of “the common interest.” Marcus also has one use,
and it moves explicitly to the other pole of appropriation—namely, to that which lends to the “care
for others” or human fellowship (3.9), and our ruling reason is what enables us to keep in accord with
nature and effect such appropriation. The related verbal and adjectival forms of “appropriating” and
being “fitting or appropriate” are more common to both.
Orexis (ὄρεξις): desire, inclination toward a thing. The opposite of ekklisis. In Aristotle this was
understood as “appetence” and was something shared with animals and different from purposive
choice (prohairesis), which involved both reason and deliberation. Epictetus says if we want to be
free, we shouldn’t desire something in someone else’s control (Discourses 1.4.18–22). Orexis/ekklisis
are the subject of the first of the three topoi, or areas of training that produce self-coherence, the other
two being hormê/aphormê and synkatathesis (3.2.1–3a). The word appears fifty-six times in the
Discourses and seven times in the Enchiridion. It appears five times in Marcus, once in saying
principles need to be the source of desire and action (8.1.5) and be limited to only what’s in our