15 The following passage is a convincing proof that he holds the transmigration of souls and annihilation of bodies. “If it can be shown that an incorporeal and reasonable being has life in itself independently of the body and that it is worse off in the body than out of it; then beyond a doubt bodies are only of secondary importance and arise from time to time to meet the varying conditions of reasonable creatures. Those who require bodies are clothed with them, and contrariwise, when fallen souls have lifted themselves up to better things, their bodies are once more annihilated.
They are thus ever vanishing and ever reappearing.” And to prevent us from minimizing the impiety of his previous utterances he ends his work by maintaining that all reasonable beings, that is, the Father, the Son, and the Holy Ghost, angels, powers, dominations, and virtues, and even man by right of his soul's dignity, are of one and the same essence. “God,” he writes, “and His only-begotten Son and the Holy Spirit are conscious of an intellectual and reasonable nature. But so also are the angels, the powers, and the virtues, as well as the inward man who is created in the image and after the likeness of God. From which I conclude that God and they are in some sort of one essence.”
He adds “in some sort” to escape the charge of blasphemy; and while in another place he will not allow the Son and the Holy Spirit to be of one substance with the Father lest by so doing he should appear to make the divine essence divisible, he here bestows the nature of God almighty upon angels and men.
Source: Letters (New Advent)