The doctors called the Holy Trinity co-essential, that through this word, composed in so polished and very sublime a way, they might express both the fact of the oneness of essence1 and that of the division of hypostases, by the same expression both union and division, in one word. For, when the Son is said to be co-essential with the Father and the Holy Spirit, he claims to share in essence with those who are recounted, but to differs in hypostasis.