Luke 1:27

For if she had had no husband, soon would the thought have stolen into the Devil's mind, how she who had known no man could be pregnant. It was right that the conception should be Divine, something more exalted than human nature.

(de san. Virg. cap. vi.) To a virgin, for Christ could be born from virginity alone, seeing He could not have an equal in His birth. It was necessary for our Head by this mighty miracle to be born according to the flesh of a virgin, that He might signify that his members were to be born in the spirit of a virgin Church.

(in Esai. 6.) The heavenly spirits visit us, not as it seems fit to them, but as the occasion conduces to our advantage, for they are ever looking upon the glory and fulness of the Divine Wisdom; hence it follows, The angel Gabriel was sent.

Scripture has rightly mentioned that she was espoused, as well as a virgin, a virgin, that she might appear free from all connection with man; espoused, that she might not be branded with the disgrace of sullied virginity, whose swelling womb seemed to bear evident marks of her corruption. But the Lord had rather that men should cast a doubt upon His birth than upon His mother's purity. He knew how tender is a virgin's modesty, and how easily assailed the reputation of her chastity, nor did He think the credit of His birth was to be built up by His mother's wrongs. It follows therefore, that the holy Mary's virginity was of as untainted purity as it was also of unblemished reputation. Nor ought there, by an erroneous opinion, to be left the shadow of an excuse to living virgins, that the mother of our Lord even seemed to be evil spoken of. But what could be imputed to the Jews, or to Herod, if they should seem to have persecuted an adulterous offspring? And how could He Himself say, I came not to abolish the law, but to fulfil it, (Matt. 5:18.) if He should seem to have had his beginning from a violation of the law, for the issue of an unmarried person is condemned by the law? (Deut. 23:17.) Not to add that also greater credit is given to the words of Mary, and the cause of falsehood removed? For it might seem that unmarried becoming pregnant, she had wished to shade her guilt by a lie; but an espoused person has no reason for lying, since to women child-birth is the reward of wedlock, the grace of the marriage bed. Again, the virginity of Mary was meant to baffle the prince of the world, who, when he perceived her espoused to a man, could cast no suspicion on her offspring. But still more has it baffled the princes of the world, for the malice of devils soon detects even hidden things, while they who are occupied in worldly vanities, can not know the things of God. But moreover, a more powerful witness of her purity is adduced, her husband, who might both have been indignant at the injury, and revenged the dishonour, if he also had not acknowledged the mystery; of whom it is added, Whose name was Joseph, of the house of David.

(sup. Mat. Hom. 4.) The angel announces the birth to the virgin not after the conception, lest she should be thereby too much troubled, but before the conception he addresses her, not in a dream, but standing by her in visible shape. For as great indeed were the tidings she receives, she needed before the issue of the event an extraordinary visible manifestation.