Thomas Aquinas

“ Thus we may say, as to the first perfection, that the marriage of the Virgin Mother of God and Joseph was absolutely true: because both consented to the nuptial bond, but not expressly to the bond of the flesh, save on the condition that it was pleasing to God. For this reason the angel calls Mary the wife of Joseph, saying to him (Mat. 1:20) : "Fear not to take unto thee Mary thy wife": on which words Augustine says (De Nup. et Concup. i) : "She is called his wife from the first promise of her espousals, whom he had not known nor ever was to know by carnal intercourse." ”

“ As Augustine says (De Trin. iii) , the devil can do many things by his natural power which he is hindered by the Divine power from doing. Thus it may be that by his natural power the devil could know that the Mother of God knew not man, but was a virgin; yet was prevented by God from knowing the manner of the Divine Birth. That afterwards the devil after a fashion knew that He was the Son of God, makes no difficulty: because then the time had already come for Christ to make known His power against the devil, and to suffer persecution aroused by him. ”

“ If she had not been espoused when pregnant, she would seem to have wished to hide her sin by a lie: being espoused, she had no motive for lying, since a woman's pregnancy is the reward of marriage and gives grace to the nuptial bond." These two reasons add strength to our faith. ”

“ Whether there was true marriage between our Lord's Mother and Joseph?
Art. 1 - Whether Christ should have been born of an espoused virgin? Objection 1: It would seem that Christ should not have been born of an espoused virgin. For espousals are ordered to carnal intercourse. But our Lord's Mother never wished to have carnal intercourse with her husband ”

“ He Who came into the world, according to the custom of the world had to be enrolled Now for this purpose, it is the men that are required, because they represent the family in the senate and other courts. ”