Chapter 66 [!]

One should know that the hypostatic union produces one compound hypostasis of the thing united and that this preserves unconfused and unaltered in itself both the uniting natures and their difference as well as their natural properties, Moreover, this has no hypostatic difference with itself, because those characteristic differences of the things uniting, by which each of them is distinguished from others of the same species, become its own. Thus it is with the hypostasis in the case of the soul and the body, for here one hypostasis is made of both—the compound hypostasis of Peter, let us say, or of Paul. This keeps in itself the two perfect natures—that of the soul and that of the body— and it preserves their difference distinct and their properties unconfused. And in itself it has the characteristic differences of each, those of the soul, which distinguish it from all other souls, and those of the body, which distinguish it from all other bodies. These, however, in no wise separate the soul from the body, but they unite and bind them together, at the same time marking off the one hypostasis composed of them from all other hypostases of the same species. Moreover, once the natures become hypostatically united, they remain absolutely indivisible. And this is so because, even though the soul is separated from the body in death, the hypostasis of both remains one and the same. For the constitution in itself of each thing at its beginning of being is a hypostasis. Therefore, the body remains, as does the soul; both always having the one principle of their being and subsistence, even though they are separated.

It is further necessary to know that it is possible for natures to be united to each other hypostatically, as in the case of man, and that it is also possible for the hypostasis to assume an additional nature. Both of these are to be observed in Christ, because in Him the divine and human natures were united, while His animate body subsisted in the pre-existent hypostasis of God the Word and had this for a hypostasis. It is, however, quite impossible for one compound nature to be made from two natures or for one hypostasis to be made from two, because it is impossible for contrary essential differences to exist together in one nature. This is because it is of the very nature of these to distinguish from each other the natures i