The prospective student of Stoic ethics who tries, perhaps naïvely, to find out what the proper entrance might be to the apparent labyrinth the Stoics so proudly proclaimed as their system, will soon come across a topic called oikeiōsis. The Greek term is usually not translated, but transliterated; not because it is untranslatable, but because any translation would seem to be intolerably clumsy. What it means can perhaps be rendered as ‘recognition and appreciation of something as belonging to one’; the corresponding verb, which is actually more prominent in the earlier sources, oikeiousthai pros ti, as ‘coming to be (or being made to be) well-disposed towards something’. It will do no harm, I think, to keep the transliteration as a convenient label.

Oikeiōsis, then, appears as the first chapter of several ancient accounts of Stoic ethics. If one turns to the experts for some guidance as to its importance, one finds that some seem to place great weight on it – Pohlenz says it was the foundation of Stoic ethics, Pembroke even claims that ‘if there had been no oikeiōsis, there would have been no Stoa’ – while others tend to play it down, saying that it is just one way of arguing for the fundamental axiom of Stoic ethics, as Brink does, or that Zeno needed it to introduce some differentiation into the field of things declared to be totally indifferent by the Cynics (Rist).