38. Are we, then, to say that the Holy Spirit is the Father of Christ's human nature, so that as God the Father generated the Word, so the Holy Spirit generated the human nature, and that from both natures Christ came to be one, Son of God the Father as the Word, Son of the Holy Spirit as man? Do we suppose that the Holy Spirit is his Father through begetting him of the Virgin Mary? Who would dare to say such a thing? There is no need to show by argument how many absurd consequences such a notion has, when it is so absurd in itself that no believer's ear can bear to hear it. Actually, then, as we confess our Lord Jesus Christ, who is God from God yet born as man of the Holy Spirit and the Virgin Mary, there is in each nature (in both the divine and the human) the only Son of God the Father Almighty, from whom proceeds the Holy Spirit.
How, then, do we say that Christ is born of the Holy Spirit, if the Holy Spirit did not beget him? Is it because he made him? This might be, since through our Lord Jesus Christ-in the form of God-all things were made. Yet in so far as he is man, he himself was made, even as the apostle says: "He was made of the seed of David according to the flesh."  But since that creature which the Virgin conceived and bore, though it was related to the Person of the Son alone, was made by the whole Trinity-for the works of the Trinity are not separable-why is the Holy Spirit named as the One who made it? Is it, perhaps, that when any One of the Three is named in connection with some divine action, the whole Trinity is to be understood as involved in that action? This is true and can be shown by examples, but we should not dwell too long on this kind of solution.
For what still concerns us is how it can be said, "Born of the Holy Spirit," when he is in no wise the Son of the Holy Spirit? Now, just because God made [fecit] this world, one could not say that the world is the son of God, or that it is "born" of God. Rather, one says it was "made" or "created" or "founded" or "established" by him, or however else one might like to speak of it. So, then, when we confess, "Born of the Holy Spirit and the Virgin Mary," the sense in which he is not the Son of the Holy Spirit and yet is the son of the Virgin Mary, when he was born both of him and of her, is difficult to explain. But there is no doubt as to the fact that he was not born from him as Father as he was born of her as mother.
39. Consequently we should not grant that whatever is born of something should therefore be called the son of that thing. Let us pass over the fact that a son is "born" of a man in a different sense than a hair is, or a louse, or a maw worm-none of these is a son. Let us pass over these things, since they are an unfitting analogy in so great a matter. Yet it is certain that those who are born of water and of the Holy Spirit would not properly be called sons of the water by anyone. But it does make sense to call them sons of God the Father and of Mother Church. Thus, therefore, the one born of the Holy Spirit is the son of God the Father, not of the Holy Spirit.
What we said about the hair and the other things has this much relevance, that it reminds us that not everything which is "born" of something is said to be "son" to him from which it is "born." Likewise, it does not follow that those who are called sons of someone are always said to have been born of him, since there are some who are adopted. Even those who are called "sons of Gehenna" are not born of it, but have been destined for it, just as the sons of the Kingdom are destined for that.
40. Wherefore, since a thing may be "born" of something else, yet not in the fashion of a "son," and conversely, since not everyone who is called son is born of him whose son he is called-this is the very mode in which Christ was "born" of the Holy Spirit (yet not as a son), and of the Virgin Mary as a son-this suggests to us the grace of God by which a certain human person, no merit whatever preceding, at the very outset of his existence, was joined to the Word of God in such a unity of person that the selfsame one who is Son of Man should be Son of God, and the one who is Son of God should be Son of Man. Thus, in his assumption of human nature, grace came to be natural to that nature, allowing no power to sin. This is why grace is signified by the Holy Spirit, because he himself is so perfectly God that he is also called God's Gift. Still, to speak adequately of this-even if one could-would call for a very long discussion.