Ante-Nicene Fathers, Vol III:
Tertullian: Part II: The Word of God Did Not Become Flesh Except in the Virgin's Womb and of Her Substance.  Through His Mother He is Descended from Her Great Ancestor David. He is Described Both in the Old and in the New Testament as “The Fruit of David's Loins.”

Chapter XXI.—The Word of God Did Not Become Flesh Except in the Virgin’s Womb and of Her Substance. Through His Mother He is Descended from Her Great Ancestor David. He is Described Both in the Old and in the New Testament as “The Fruit of David’s Loins.”

Whereas, then, they contend that the novelty (of Christ’s birth) consisted in this, that as the Word of God became flesh without the seed of a human father, so there should be no flesh of the virgin mother (assisting in the transaction), why should not the novelty rather be confined to this, that His flesh, although not born of seed, should yet have proceeded from flesh? I should like to go more closely into this discussion.  “Behold,” says he, “a virgin shall conceive in the womb.” 7228 Conceive what? I ask. The Word of God, of course, and not the seed of man, and in order, certainly, to bring forth a son. “For,” says he, “she shall bring forth a son.” 7229 Therefore, as the act of conception was her own, 7230 so also what she brought forth was her own, also, although the cause of conception 7231 was not. If, on the other hand, the Word became flesh of Himself, then He both conceived and brought forth Himself, and the prophecy is stultified. For in that case a virgin did not conceive, and did not bring forth; since whatever she brought forth from the conception of the Word, is not her own flesh. But is this the only statement of prophecy which will be frustrated? 7232 Will not the angel’s announcement also be subverted, that the virgin should “conceive in her womb and bring forth a son?” 7233 And will not in fact every scripture which declares that Christ had a mother? For how could she have been His mother, unless He had been in her womb? But then He received nothing from her womb which could make her a mother in whose womb He had been. 7234 Such a name as this 7235 a strange flesh ought not to assume. No flesh can speak of a mother’s womb but that which is itself the offspring of that womb; nor can any be the offspring of the said womb if it owe its p. 540 birth solely to itself. Therefore even Elisabeth must be silent although she is carrying in her womb the prophetic babe, which was already conscious of his Lord, and is, moreover, filled with the Holy Ghost. 7236 For without reason does she say, “and whence is this to me that the mother of my Lord should come to me?” 7237 If it was not as her son, but only as a stranger that Mary carried Jesus in her womb, how is it she says, “Blessed is the fruit of thy womb”? 7238 What is this fruit of the womb, which received not its germ from the womb, which had not its root in the womb, which belongs not to her whose is the womb, and which is no doubt the real fruit of the womb—even Christ? Now, since He is the blossom of the stem which sprouts from the root of Jesse; since, moreover, the root of Jesse is the family of David, and the stem of the root is Mary descended from David, and the blossom of the stem is Mary’s son, who is called Jesus Christ, will not He also be the fruit?  For the blossom is the fruit, because through the blossom and from the blossom every product advances from its rudimental condition 7239 to perfect fruit. What then? They, deny to the fruit its blossom, and to the blossom its stem, and to the stem its root; so that the root fails to secure 7240 for itself, by means of the stem, that special product which comes from the stem, even the blossom and the fruit; for every step indeed in a genealogy is traced from the latest up to the first, so that it is now a well-known fact that the flesh of Christ is inseparable, 7241 not merely from Mary, but also from David through Mary, and from Jesse through David. “This fruit,” therefore, “of David’s loins,” that is to say, of his posterity in the flesh, God swears to him that “He will raise up to sit upon his throne.” 7242 If “of David’s loins,” how much rather is He of Mary’s loins, by virtue of whom He is in “the loins of David?”

Footnotes

Isa. 7:14, Matt. 1:23.

See the same passages.

Ipsius.

Quod concepit: or, “what she conceived.”

Evacuabitur.

Luke i. 31.

An objection.

The rejoinder.

Luke i. 41.

Luke 1.43.

Luke 1.42.

Eruditur.

Quominus vindicet.

Adhærere.

Ps. 132:11, Acts 2:30.