Thomas Aquinas - Summa Theologica, Part III (Tertia Pars)

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."

Reply Obj. 1: The work of the conception is indeed common to the whole Trinity; yet in some way it is attributed to each of the Persons. For to the Father is attributed authority in regard to the Person of the Son, who by this conception took to Himself (human nature). The taking itself (of human nature) is attributed to the Son: but the formation of the body taken by the Son is attributed to the Holy Ghost. For the Holy Ghost is the Spirit of the Son, according to Gal. 4:6: "God sent the Spirit of His Son." For just as the power of the soul which is in the semen, through the spirit enclosed therein, fashions the body in the generation of other men, so the Power of God, which is the Son Himself, according to 1 Cor. 1:24: "Christ, the Power of God," through the Holy Ghost formed the body which He assumed. This is also shown by the words of the angel: "The Holy Ghost shall come upon thee," as it were, in order to prepare and fashion the matter of Christ's body; "and the Power of the Most High," i.e. Christ, "shall overshadow thee—that is to say, the incorporeal Light of the Godhead shall in thee take the corporeal substance of human nature: for a shadow is formed by light and body," as Gregory says (Moral. xviii). The "Most High" is the Father, whose Power is the Son.

Reply Obj. 2: The mission refers to the Person assuming, who is sent by the Father; but the conception refers to the body assumed, which is formed by the operation of the Holy Ghost. And therefore, though mission and conception are in the same subject; since they differ in our consideration of them, mission is attributed to the Father, but the accomplishment of the conception to the Holy Ghost; whereas the assumption of flesh is attributed to the Son.

Reply Obj. 3: As Augustine says (QQ. Vet. et Nov. Test., qu. 52): "This may be understood in two ways. For, first, Christ's house is the Church, which He built with His blood. Secondly, His body may be called His house, just as it is called His temple . . . and what is done by the Holy Ghost is done by the Son of God, because Theirs is one Nature and one Will." _______________________

SECOND ARTICLE [III, Q. 32, Art. 2]

Whether It Should Be Said That Christ Was Conceived of ( de ) the Holy Ghost?

Objection 1: It would seem that we should not say that Christ was conceived of ( de ) the Holy Ghost. Because on Rom. 11:36: "For of Him ( ex ipso ) and by Him, and in Him, are all things," the gloss of Augustine says: "Notice that he does not say, 'of Him' ( de ipso ), but 'of Him' ( ex ipso ). For of Him ( ex ipso ), are heaven and earth, since He made them: but not of Him [de ipso, since they are not made of His substance." But the Holy Ghost did not form Christ's body of ( de ) His own substance. Therefore we should not say that Christ was conceived of ( de ) the Holy Ghost.

Obj. 2: Further, the active principle of ( de ) which something is conceived is as the seed in generation. But the Holy Ghost did not take the place of seed in Christ's conception. For Jerome says (Expos. Cathol. Fidei) [*Written by Pelagius]: "We do not say, as some wicked wretches hold, that the Holy Ghost took the place of seed: but we say that Christ's body was wrought," i.e. formed, "by the power and might of the Creator." Therefore we should not say that Christ's body was conceived of ( de ) the Holy Ghost.

Obj. 3: Further, no one thing is made of two, except they be in some way mingled. But Christ's body was formed of ( de ) the Virgin Mary. If therefore we say that Christ was conceived of ( de ) the Holy Ghost, it seems that a mingling took place of the Holy Ghost with the matter supplied by the Virgin: and this is clearly false. Therefore we should not say that Christ was conceived of ( de ) the Holy Ghost.

On the contrary, It is written (Matt. 1:18): "Before they came together, she was found with child, of ( de ) the Holy Ghost."

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.

Reply Obj. 1: Christ's body, through not being consubstantial with the Holy Ghost, cannot properly be said to be conceived "of" ( de ) the Holy Ghost, but rather "from ( ex ) the Holy Ghost," as Ambrose says (De Spir. Sanct. ii.): "What is from someone is either from his substance or from his power: from his substance, as the Son who is from the Father; from his power, as all things are from God, just as Mary conceived from the Holy Ghost."

Reply Obj. 2: It seems that on this point there is a difference of opinion between Jerome and certain other Doctors, who assert that the Holy Ghost took the place of seed in this conception. For Chrysostom says (Hom. i in Matth. [*Opus Imperf., among the supposititious writings]): "When God's Only-Begotten was about to enter into the Virgin, the Holy Ghost preceded Him; that by the previous entrance of the Holy Ghost, Christ might be born unto sanctification according to His body, the Godhead entering instead of the seed." And Damascene says (De Fide Orth. iii): "God's wisdom and power overshadowed her, like unto a Divine seed."

But these expressions are easily explained. Because Chrysostom and Damascene compare the Holy Ghost, or also the Son, who is the Power of the Most High, to seed, by reason of the active power therein; while Jerome denies that the Holy Ghost took the place of seed, considered as a corporeal substance which is transformed in conception.

Reply Obj. 3: As Augustine says (Enchiridion xl), Christ is said to be conceived or born of the Holy Ghost in one sense; of the Virgin Mary in another—of the Virgin Mary materially; of the Holy Ghost efficiently. Therefore there was no mingling here. _______________________

THIRD ARTICLE [III, Q. 32, Art. 3]

Whether the Holy Ghost Should Be Called Christ's Father in Respect of

His Humanity?

Objection 1: It would seem that the Holy Ghost should be called Christ's father in respect of His humanity. Because, according to the Philosopher (De Gener. Animal. i): "The Father is the active principle in generation, the Mother supplies the matter." But the Blessed Virgin is called Christ's Mother, by reason of the matter which she supplied in His conception. Therefore it seems that the Holy Ghost can be called His father, through being the active principle in His conception.