OIKEIOSIS is ‘self-ownership’. Other possible translations to English are ‘appropriation’, ‘orientation’, ‘familiarization’, ‘affinity’, ‘affiliation’, and even ‘endearment’. Anyway, the Latin translation is <conciliatio>. Nonetheless, in our philosophical discourse, <oikeiôsis> is the perception of something as one’s own, as belonging to oneself.

The development of this notion goes back to the work of the Stoic philosopher, Zenon ho Kitieus (Zeno of Citium). Moreover, another Stoic thinker, Hierocles, sees <oikeiosis> as the basis for all animal impulses as well as for human ethical action.

In his Elements of Ethics, Hierocles considers the life of animals. In the earliest step of perception, an animal realizes its body. Furthermore, it recognizes its sensations as “belonging to itself”. Such an awareness is <proton oikeion>, that is “the first thing that is one’s own and familiar“. And it is constant as well as deriving from the perception of external objects. For Hierocles, this phenomenon explains why children are fearful of the dark. Their feeble “sense of self” fears death when there are no external entities. Hierocles maintains that the impulse of self-preservation derives from <oikeiôsis>. “An animal, when it receives the first perception of itself, immediately becomes its own and familiar to itself and to its constitution“. In perceiving itself and becoming familiar to itself, an animal finds value in itself and its own well-being.

<Oikeiosis> is ‘self-ownership’. Hierocles differentiates the various kinds of <oikeiôsis> between internal and external. Internal ones include appropriation of the self as well as of one’s constitution. External forms include familiarization with other people and an orientation towards external goods.