Of the Active Principle in Christ's Conception

I answer that, The whole Trinity effected the conception of Christ's body: nevertheless, this is attributed to the Holy Ghost, for three reasons. First, because this is befitting to the cause of the Incarnation, considered on the part of God. For the Holy Ghost is the love of Father and Son, as stated in the First Part (Q. 37, A. 1). Now, that the Son of God took to Himself flesh from the Virgin's womb was due to the exceeding love of God: wherefore it is said (John 3:16): "God so loved the world as to give His only-begotten Son."

Secondly, this is befitting to the cause of the Incarnation, on the part of the nature assumed. Because we are thus given to understand that human nature was assumed by the Son of God into the unity of Person, not by reason of its merits, but through grace alone; which is attributed to the Holy Ghost, according to 1 Cor. 12:4: "There are diversities of graces, but the same Spirit." Wherefore Augustine says (Enchiridion xl): "The manner in which Christ was born of the Holy Ghost . . . suggests to us the grace of God, whereby man, without any merits going before, in the very beginning of his nature when he began to exist was joined to God the Word, into so great unity of Person, that He Himself should be the Son of God."

Thirdly, because this is befitting the term of the Incarnation. For the term of the Incarnation was that that man, who was being conceived, should be the Holy one and the Son of God. Now, both of these are attributed to the Holy Ghost. For by Him men are made to be sons of God, according to Gal. 4:6: "Because you are sons, God hath sent the Spirit of His Son into your [Vulg.: 'our'] hearts, crying: Abba, Father." Again, He is the "Spirit of sanctification," according to Rom. 1:4. Therefore, just as other men are sanctified spiritually by the Holy Ghost; so as to be the adopted sons of God, so was Christ conceived in sanctity by the Holy Ghost, so as to be the natural Son of God. Hence, according to a gloss on Rom. 1:4, the words, "Who was predestinated the Son of God, in power," are explained by what immediately follows: "According to the Spirit of sanctification, i.e. through being conceived of the Holy Ghost." And the Angel of the Annunciation himself, after saying, "The Holy Ghost shall come upon thee," draws the conclusion: "Therefore also the Holy which shall be born of thee shall be called the Son of God."

I answer that, Conception is not attributed to Christ's body alone, but also to Christ Himself by reason of His body. Now, in the Holy Ghost we may observe a twofold habitude to Christ. For to the Son of God Himself, who is said to have been conceived, He has a habitude of consubstantiality: while to His body He has the habitude of efficient cause. And this preposition of (de) signifies both habitudes: thus we say that a certain man is "of (de) his father." And therefore we can fittingly say that Christ was conceived of the Holy Ghost in such a way that the efficiency of the Holy Ghost be referred to the body assumed, and the consubstantiality to the Person assuming.

I answer that, The words "fatherhood," "motherhood," and "sonship," result from generation; yet not from any generation, but from that of living things, especially animals. For we do not say that fire generated is the son of the fire generating it, except, perhaps, metaphorically; we speak thus only of animals in whom generation is more perfect. Nevertheless, the word "son" is not applied to everything generated in animals, but only to that which is generated into likeness of the generator. Wherefore, as Augustine says (Enchiridion xxxix), we do not say that a hair which is generated in a man is his son; nor do we say that a man who is born is the son of the seed; for neither is the hair like the man nor is the man born like the seed, but like the man who begot him. And if the likeness be perfect, the sonship is perfect, whether in God or in man. But if the likeness be imperfect, the sonship is imperfect. Thus in man there is a certain imperfect likeness to God, both as regards his being created to God's image and as regards His being created unto the likeness of grace. Therefore in both ways man can be called His son, both because he is created to His image and because he is likened to Him by grace. Now, it must be observed that what is said in its perfect sense of a thing should not be said thereof in its imperfect sense: thus, because Socrates is said to be naturally a man, in the proper sense of "man," never is he called man in the sense in which the portrait of a man is called a man, although, perhaps, he may resemble another man. Now, Christ is the Son of God in the perfect sense of sonship. Wherefore, although in His human nature He was created and justified, He ought not to be called the Son of God, either in respect of His being created or of His being justified, but only in respect of His eternal generation, by reason of which He is the Son of the Father alone. Therefore nowise should Christ be called the Son of the Holy Ghost, nor even of the whole Trinity.

I answer that, Some say that the Blessed Virgin cooperated actively in Christ's conception, both by natural and by a supernatural power. By natural power, because they hold that in all natural matter there is an active principle; otherwise they believe that there would be no such thing as natural transformation. But in this they are deceived. Because a transformation is said to be natural by reason not only of an active but also of a passive intrinsic principle: for the Philosopher says expressly (Phys. viii) that in heavy and light things there is a passive, and not an active, principle of natural movement. Nor is it possible for matter to be active in its own formation, since it is not in act. Nor, again, is it possible for anything to put itself in motion except it be divided into two parts, one being the mover, the other being moved: which happens in animate things only, as is proved Phys. viii.

By a supernatural power, because they say that the mother requires not only to supply the matter, which is the menstrual blood, but also the semen, which, being mingled with that of the male, has an active power in generation. And since in the Blessed Virgin there was no resolution of semen, by reason of her inviolate virginity, they say that the Holy Ghost supernaturally bestowed on her an active power in the conception of Christ's body, which power other mothers have by reason of the semen resolved. But this cannot stand, because, since "each thing is on account of its operation" (De Coel. ii), nature would not, for the purpose of the act of generation, distinguish the male and female sexes, unless the action of the male were distinct from that of the female. Now, in generation there are two distinct operations—that of the agent and that of the patient. Wherefore it follows that the entire active operation is on the part of the male, and the passive on the part of the female. For this reason in plants, where both forces are mingled, there is no distinction of male and female.

Since, therefore, the Blessed Virgin was not Christ's Father, but His Mother, it follows that it was not given to her to exercise an active power in His conception: whether to cooperate actively so as to be His Father, or not to cooperate at all, as some say. Whence it would follow that this active power was bestowed on her to no purpose. We must therefore say that in Christ's conception itself she did not cooperate actively, but merely supplied the matter thereof. Nevertheless, before the conception she cooperated actively in the preparation of the matter so that it should be apt for the conception.