Chapter 45 — That it was fitting that Christ should be born of a virgin

Hence it follows that this man had to be born of a virgin mother, without natural seed.

The seed of the male is required as the active principle in human generation on account of the active power it contains. Now, according to what has been said, the active power in the generation of Christ could not be natural, since the natural power does not instantly cause the entire formation of the body, but needs time for that purpose. But the body of Christ was formed and limbed from the first moment of its conception, as we have proved. (Ch. 44.) Therefore, the human generation of Christ was without natural seed.

Again. In the generation of any animal, the seed of the male draws to itself the matter provided by the female, as though the power contained in it aimed at its own perfection as the end of the whole process of generation. Hence, as soon as this process is complete, the seed itself, developed and complete, is the offspring that is born. Now, in the human generation of Christ, the ultimate term of generation was union with the divine person, but not the formation of a human person or hypostasis, as proved above. (Ch. 41.) Therefore, in this generation, the active principle could not be the seed of a man, but the power of God alone, so that even as in the ordinary generation of man, the seed of the male attracts to itself the matter provided by the female, so, in the generation of Christ, the Word of God took the same matter into union with himself.

In like manner, it is clear that even in the human generation of God’s Word, there should be evidence of some property of the spiritual generation of the Word. Now a word as produced by the utterer (whether by interior concept, or by outward speech) causes no detriment to the utterer; indeed, rather does it perfect him. Therefore, it was fitting that in the process of his human generation, the Word of God should be so conceived and born, that the integrity of his mother should remain intact. Besides, clearly the Word of God, by whom all things were made and preserved in their integrity, had to be born in such a manner that his mother’s integrity remained wholly unimpaired. Consequently, it was fitting that he should be born of a virgin.

Nor is this manner of generation derogatory to the true and natural human nature of Christ, although he was begotten otherwise than other men. For, seeing that God’s power is infinite, as proved above, (Bk. 1, ch. 43.) and that all causes derive from it their power of producing an effect, it is evident that any effect whatsoever that is produced by any cause can, in the same species and nature, be produced by God, without the aid of that cause. Therefore, just as the natural power in human seed produces a real man, having the human species and nature, so too the divine power which endowed the seed with that power can produce the effects of that power by forming a real man (having the human species and nature) without its assistance.

Someone, however, may object that in order to be begotten naturally, a man’s body must be fashioned naturally from the seed of a man, and from whatever it is that the woman supplies; therefore, Christ’s body was not of the same nature as ours if it was not begotten of a man’s seed. But this objection is easily answered according to Aristotle’s opinion, (Aristotle, Generation of Animals, bk. 1.) who held that the seed of the male does not form a substantial part of the embryo, but is merely the active principle; and that the whole matter of the body is supplied by the mother. Accordingly, as regards its matter, Christ’s body differs not from ours, because our bodies also are formed from the material supplied by the mother.

But even if one were not to admit this opinion of Aristotle, the above objection would not stand. For likeness or unlikeness, as regards matter, depends not on the condition of the matter at the beginning of generation, but on its condition when generation is terminated. Thus air generated from earth does not differ from air generated from water, because though earth and water differ at the beginning of the process, the action of the generator brings them to a same state of being. Accordingly, the material that is taken from the woman only can by God’s power be brought to the same state, when the process of generation is terminated, as would result were the material taken from both man and woman. Consequently, there will be no unlikeness through difference of material between Christ’s body, which was formed by God’s power from material taken from his mother only, and our bodies, which are formed by nature’s power, although the material from which they are fashioned is taken from both parents. Thus the slime of the earth from which God formed the first man (who without doubt was a real man, and like us in every way) surely differs more from the material taken from both parents than does the material taken from the woman only, from which Christ’s body was formed. Consequently, Christ’s birth of a virgin is in no way derogatory either to the reality of his human nature, or to his likeness to us. For although the forces of nature require definite material for a definite effect to be produced from it, the power of God (which can produce all things out of nothing) is not confined to definite material in his action.

Neither does it derogate from the dignity of Christ’s mother that she was a virgin both in conceiving and in giving birth, so as to forbid us to hail her as the true and natural mother of God’s Son. Through the agency of the divine power, she supplied the natural matter for the generation of Christ’s body, and this is all that is required on the mother’s part. But all that conduces to the loss of virginity in other mothers is directed not to motherhood, but to fatherhood, its purpose being that the seed of the male may reach the place adapted for generation.