Excepting, therefore, all these things as I just now said, there are some also of another kind; which, although from the same corporeal substance, are yet brought within reach of our senses in order to announce something from God, and these are properly called miracles and signs; yet is not the person of God Himself assumed in all things which are announced to us by the Lord God. When, however, that person is assumed, it is sometimes made manifest as an angel; sometimes in that form which is not an angel in his own proper being, although it is ordered and ministered by an angel. Again, when it is assumed in that form which is not an angel in his own proper being; sometimes in this case it is a body itself already existing, assumed after some kind of change, in order to make that message manifest; sometimes it is one that comes into being for the purpose, and that being accomplished, is discarded. Just as, also, when men are the messengers, sometimes they speak the words of God in their own person, as when it is premised, “The Lord said,” or, “Thus saith the Lord,” or any other such phrase, but sometimes without any such prefix, they take upon themselves the very person of God, as e.g.: “I will instruct thee, and teach thee in the way wherein thou shalt go:” so, not only in word, but also in act, the signifying of the person of God is imposed upon the prophet, in order that he may bear that person in the ministering of the prophecy; just as he, for instance, bore that person who divided his garment into twelve parts, and gave ten of them to the servant of King Solomon, to the future king of Israel. Sometimes, also, a thing which was not a prophet in his own proper self, and which existed already among earthly things, was assumed in order to signify this; as Jacob, when he had seen the dream, upon waking up did with the stone, which when asleep he had under his head. Sometimes a thing is made in the same kind, for the mere purpose; so as either to continue a little while in existence, as that brazen serpent was able to do which was lifted up in the wilderness, and as written records are able to do likewise; or so as to pass away after having accomplished its ministry, as the bread made for the purpose is consumed in the receiving of the sacrament.
Complete source paragraph · On the Holy Trinity, Chapter 10.—In How Many Ways the Creature is to Be Taken by Way of Sign. The Eucharist.; original source section: Chapter 11, source paragraph 2 · Original source