I have proposed to clarify and explain the concepts of hypostasis and essence, or of person and nature (for both [pairs] are the same, and each refers to the same thing), …

… Hypostasis, gentlemen, and the hypostatic are not the same thing, just as essence and the essential are different. For the hypostasis signifies the individual, but the hypostatic the essence; and the hypostasis defines the person by means of peculiar characteristics, while the hypostatic signifies that something is not an accident, which has its being in another and is not perceived by itself. Such are all qualities, those called essential and those called non-essential; neither of them is the essence, which is a subsistent thing—but is perceived always in association with an essence, as with color in a body or knowledge in a soul. He then who says, “There is no such thing as an anhypostatic nature,” speaks truly; but he does not draw a correct conclusion when he argues from its being not-anhypostatic to its being an hypostasis — just as if one should say, correctly, that there is no such thing as a body without form, but then conclude incorrectly that form is body, not that it is seen in the body. There could never, then, be an anhypostatic nature—that is, essence. But the nature is not a hypostasis, because it is not a reversible attribution; for a hypostasis is also a nature, but a nature is not also a hypostasis: for nature admits of the predication of being, but hypostasis also of being-by-oneself, and the former presents the character of genus, the latter expresses individual identity. And the one brings out what is peculiar to something universal, the other distinguishes the particular from the general. To put it concisely, things sharing the same essence are properly said to be of one nature, and things whose structure of being is common; but we can define as *hypostasis" either things which share a nature but differ in number, or things which are put together from different natures, but which share reciprocally in a common being. I say that they share being, not as if they completed one another’s essence, as happens with essences and with things that are essentially predicated of them — which are called qualities — but insofar as the nature and essence of each is not considered by itself but with the other, to which it is joined and assimilated. One finds this in various things, not least in the case of soul and body, whose hypostasis is common but each of whose natures is individual, with a different way of being.