The Catechism of St. Thomas Aquinas: THE THIRD ARTICLE

“Who was conceived by the Holy Ghost, born of the Virgin Mary.”

The Christian must not only believe in the Son of God, as we have seen, but also in His Incarnation. St. John, after having written of things subtle and difficult to understand,[1] points out the Incarnation to us when he says: “And the Word was made flesh.”[2] Now, in order that we may understand something of this, I give two illustrations at the outset.

It is clear that there is nothing more like the Word of God than the word which is conceived in our mind but not spoken. Now, no one knows this interior word in our mind except the one who conives it, and then it is known to others only when it is pronounced.[3] So also as long as the Word of God was in the heart of the Father, it was not known except by the Father Himself; but when the Word assumed flesh–as a word becomes audible–then was It first made manifest and known. “Afterwards He was seen upon earth and conversed with men.”[4] Another example is that, although the spoken word is known through hearing, yet it is neither seen nor touched, unless it is written on paper. So also the Word of God was made both visible and tangible when He became flesh. And as the paper upon which the word of a king is written is called the word of the king, so also Man to whom the Word of God is conjoined in one “hypostasis”[5] is called the Son of God. “Take thee a great book and write in it with a man’s pen.”[6] Therefore, the holy Apostles affirmed: “Who was conceived by the Holy Ghost, born of the Virgin Mary.”


On this point there arose many errors; and the holy Fathers at the Council of Nicea added in that other Creed a number of things which suppress all these errors.

Origen said that Christ was born and came into the world to save even the devils, and, therefore, at the end of the world all the demons will be saved. But this is contrary to the Holy Scripture: Depart from Me, you cursed, into everlasting fire which was prepared for the devil and his angels.”[7] Consequently, to remove this error they added in the Creed: “Who for us men (not for the devils) and for our salvation, came down from heaven.” In this the love of God for us is made more


Photinus would have Christ born of the Blessed Virgin, but added that He was a mere man who by a good life in doing the will of God merited to become the son of God even as other holy men. This, too, is denied by this saying of John: “I came down from heaven, not to do My own will but the will of Him that sent Me.” 8 Now if Christ were not in heaven, He would not have descended from heaven, and were He a mere man, He would not have been in heaven. Hence, it is said in the Nicene Creed: “He came down from heaven.”

Manichaeus, however, said that Christ was always the Son of God and He descended from heaven, but He was not actually but only in appearance clothed in true flesh. But this is false, because it is not worthy of the Teacher of Truth to have anything to do with what is false, and just as He showed His physical Body, so it was really His: “Handle, and see; for a spirit hath not flesh and bones, as you see Me to have.”[9] To remove this error, therefore, they added: “And He was incarnate.”

Ebion, who was a Jew, said that Christ was born of the Blessed Virgin in the ordinary human way.[10] But this is false, for the Angel said of Mary: “That which is conceived in her is of the Holy Ghost.”[11] And the holy Fathers to destroy this error, added: “By the Holy Ghost.”

Valentinus believed that Christ was conceived by the Holy Ghost, but would have the Holy Spirit deposit a heavenly body in the Blessed Virgin, so that she contributed nothing to Christ’s birth except to furnish a place for Him. Thus, he said, this Body appeared by means of the Blessed Virgin, as though she were a channel. This is a great error, for the Angel said: “And therefore also the Holy which shall be born of thee shall be called the Son of God.”[12] And the Apostle adds: “But when the fullness of time was come, God sent His Son, made of a woman.”[13] Hence the Creed says: “Born of the Virgin Mary.”

Arius and Apollinarius held that, although Christ was the Word of God and was born of the Virgin Mary, nevertheless He did not have a soul, but in place of the soul was His divinity. This is contrary to the Scripture, for Christ says: “Now is My soul troubled.”[14] And again: “My soul is sorrowful even unto death.”[15] For this reason the Fathers added: “And was made man.” Now, man is made up of body and soul. Christ had all that a true man has save sin. All the above-mentioned errors and all others that can be offered are destroyed by this, that He was made man. The error of Eutyches particularly is destroyed by it. He held that, by a commixture of the divine nature of Christ with the human, He was neither purely divine nor purely human. This is not true, because by it Christ would not be a man. And so it is said: “He was made man.” This destroys also the error of Nestorius, who said that the Son of God only by an indwelling was united to man. This, too, is false, because by this Christ would not be man but only in a man, and that He became man is clear from these words: “He was in habit found as man.”[16] “But now you seek to kill Me, a man who have spoken the truth to you, which I have heard of God.[17]


We can learn something from all this. (1) Our faith is strengthened. If, for instance, someone should tell us about a certain foreign land which he himself had never seen, we would not believe him to the extent we would if he had been there. Now, before Christ came into the world, the Patriarchs and Prophets and John the Baptist told something of God; but men did not believe them as they believed Christ, who was with God, nay more, was one with God. Hence, far more firm is our faith in what is given us by Christ Himself: “No one hath seen God at any time; the only-begotten Son who is in the bosom of the Father, He hath declared Him.”[18] Thus, many mysteries of our faith which before the coming of Christ were hidden from us, are now made clear.

(2) Our hope is raised up. It is certain that the Son of Man did not come to us, assuming our flesh, for any trivial cause, but for our exceeding great advantage. For He made as it were a trade with us, assuming a living body and deigning to be born of the Virgin, in order that to us might be vouchsafed part of His divinity.[19] And thus He became man that He might make man divine.[20]

(3) Our charity is enkindled. There is no proof of divine charity so clear as that God, the Creator of all things, is made a creature; that Our Lord is become our brother, and that the Son of God is made the Son of man: “For God so loved the world as to give His only-begotten Son.”[21] Therefore, upon consideration of this our love for God ought to be re-ignited and burst into flame.

(4) This induces us to keep our souls pure. Our nature was exalted and ennobled by its union with God to the extent of being assumed into union with a Divine Person.[22]

Indeed, after the Incarnation the Angel would not permit St. John to adore him, although he allowed this to be done before by even the greatest patriarchs.[23] Therefore, one who reflects on this exaltation of his nature and is ever conscious of it, should scorn to cheapen and lower himself and his nature by sin. Thus, says St. Peter: “By whom He hath given us most great and precious promises; that by these you may be made partakers of the divine nature; flying the corruption of that concupiscence which is in the world.”[24]

Finally, by consideration of all this, our desire to come to Christ is intensified. If a king had a brother who was away from him a long distance, that brother would desire to come to the king to see, to be with him and to abide with him. So also Christ is our brother, and we should desire to be with Him and to be united to Him. “Wheresoever the body shall be, there shall the eagles also gathered together.”[25] The Apostle desired “to be dissolved and be with Christ.”[26] And it is this desire which grows in us as we meditate upon the Incarnation of Christ.

(For “Questions for Discussion” see Chapter 6.)


1. John, i. 1-13.

2. “Ibid.,” i. 14.

3. See above, p. 17.

4. Baruch, iii. 38.

5. Hypostasis is person distinct from nature, as in the one hypostasis of Christ as distinct from His two natures, human and divine; also distinct from substance, as in the three hypostases of the Godhead, which are the same in substance.

6. Isa., vii. 1.

7. Matt., xxv. 41.

8.John, vi. 38.

9. Luke, xxiv. 39.

10. We believe and confess that the same Jesus Christ, our only Lord, the son of God when He assumed human flesh for us in the womb of the virgin. was not conceived iike other men, from the seed of man but in a manner above the order of nature, i. e., by the power of the Holy Ghost; so that the same Person, remaining God as He was from all eternity, became man, what He was not before” (“Roman Catechism,” Third Article, 1).

11. Matt., i. 20.

12. Luke, i. 35

13. Gal., iv. 4.

14. John, xii, 27.

15. Matt., xxvi. 38.

16. Phil. ii. 7.

17. John viii. 40.

18. “Ibid.,” i. 18.

19. Thus, in the Mass, when the Priest puts wine and water in the chalice, he says: “. . . Grant that by the mystery of this water and wine we may be made partakers of His Divinity who vouchsafed to become partakers of our humanity, Jesus Christ, Thy Son, Our Lord.”

20. “Et sic factus est homo, ut hominem faceret Deum.”

21. John. iii. 16.

22. “The Word, who is a Person of the divine nature, assumed human nature in such a manner that there should be one and the same Person in both the divine and human natures” (“Roman Catechism,” “loc. cit.,” 2).

23. “And after I had heard and seen, I fell down to adore before the feet of the Angel who showed me these things. And he said to me: ‘See thou do it not’ ” (Apoc., xxii. 8).

24. II Peter, i, 4. “God deigned to assume the lowliness and frailty of our flesh in order to lift man up to the highest degree of dignity . . . We may now glory that the Son of God is bone of our bone, and flesh of our flesh, a privilege which is not granted to the Angels” (“Roman Catechism,” “loc. cit.,” 11).

25. Matt., xxiv. 28.

26. Phil., i. 23.

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