That It is Not Easy to Discover the Trinity that is God from the Trinities We Have Spoken of
11 But these three are in such way in man, that they are not themselves man. For man, as the ancients defined him, is a rational mortal animal. These things, therefore, are the chief things in man, but are not man themselves. And any one person, i.e. each individual man, has these three things in his mind. But if, again, we were so to define man as to say, Man is a rational substance consisting of mind and body, then without doubt man has a soul that is not body, and a body that is not soul. And hence these three things are not man, but belong to man, or are in man. If, again, we put aside the body, and think of the soul by itself, the mind is somewhat belonging to the soul, as though its head, or eye, or countenance; but these things are not to be regarded as bodies. It is not then the soul, but that which is chief in the soul, that is called the mind. But can we say that the Trinity is in such way in God, as to be somewhat belonging to God, and not itself God? And hence each individual man, who is called the image of God, not according to all things that pertain to his nature, but according to his mind alone, is one person, and is an image of the Trinity in his mind. But that Trinity of which he is the image is nothing else in its totality than God, is nothing else in its totality than the Trinity. Nor does anything pertain to the nature of God so as not to pertain to that Trinity; and the Three Persons are of one essence, not as each individual man is one person.
12. There is, again, a wide difference in this point likewise, that whether we speak of the mind in a man, and of its knowledge and love; or of memory, understanding, will,— we remember nothing of the mind except by memory, nor understand anything except by understanding, nor love anything except by will. But in that Trinity, who would dare to say that the Father understands neither Himself, nor the Son, nor the Holy Spirit, except by the Son, or loves them except by the Holy Spirit; and that He remembers only by Himself either Himself, or the Son, or the Holy Spirit; and in the same way that the Son remembers neither Himself nor the Father, except by the Father, nor loves them except by the Holy Spirit; but that by Himself He only understands both the Father and Son and Holy Spirit: and in like manner, that the Holy Spirit by the Father remembers both the Father and the Son and Himself, and by the Son understands both the Father and the Son and Himself; but by Himself only loves both Himself and the Father and the Son;— as though the Father were both His own memory, and that of the Son and of the Holy Spirit; and the Son were the understanding of both Himself, and the Father and the Holy Spirit; but the Holy Spirit were the love both of Himself, and of the Father and of the Son? Who would presume to think or affirm this of that Trinity? For if therein the Son alone understands both for Himself and for the Father and for the Holy Spirit, we have returned to the old absurdity, that the Father is not wise from Himself, but from the Son, and that wisdom has not begotten wisdom, but that the Father is said to be wise by that wisdom which He begot. For where there is no understanding there can be no wisdom; and hence, if the Father does not understand Himself for Himself, but the Son understands for the Father, assuredly the Son makes the Father wise. But if to God to be is to be wise, and essence is to Him the same as wisdom, then it is not the Son that has His essence from the Father, which is the truth, but rather the Father from the Son, which is a most absurd falsehood. And this absurdity, beyond all doubt, we have discussed, disproved, and rejected, in the seventh book. Therefore God the Father is wise by that wisdom by which He is His own wisdom, and the Son is the wisdom of the Father from the wisdom which is the Father, from whom the Son is begotten; whence it follows that the Father understands also by that understanding by which He is His own understanding (for he could not be Wise that did not understand); and that the Son is the understanding of the Father, begotten of the understanding which is the Father. And this same may not be unfitly said of memory also. For how is he wise, that remembers nothing, or does not remember himself? Accordingly, since the Father is wisdom, and the Son is wisdom, therefore, as the Father remembers Himself, so does the Son also remember Himself; and as the Father remembers both Himself and the Son, not by the memory of the Son, but by His own, so does the Son remember both Himself and the Father, not by the memory of the Father, but by His own. Where, again, there is no love, who would say there was any wisdom? And hence we must infer that the Father is in such way His own love, as He is His own understanding and memory. And therefore these three, i.e. memory, understanding, love or will in that highest and unchangeable essence which is God, are, we see, not the Father and the Son and the Holy Spirit, but the Father alone. And because the Son too is wisdom begotten of wisdom, as neither the Father nor the Holy Spirit understands for Him, but He understands for Himself; so neither does the Father remember for Him, nor the Holy Spirit love for Him, but He remembers and loves for Himself: for He is Himself also His own memory, His own understanding, and His own love. But that He is so comes to Him from the Father, of whom He is born. And because the Holy Spirit also is wisdom proceeding from wisdom, He too has not the Father for a memory, and the Son for an understanding, and Himself for love: for He would not be wisdom if another remembered for Him, and yet another understood for Him, and He only loved for Himself; but Himself has all three things, and has them in such way that they are Himself. But that He is so comes to Him thence, whence He proceeds.
Source: On the Holy Trinity (New Advent)