“An ancient author offered another reason. The marriage with Joseph was planned so that Mary’s virginity might remain hidden from the prince of this world. For the external forms of marriage were adopted by the Virgin, almost as if to distract the Evil One, who has always preyed on virgins, ever since he heard the prophet announcing: “Behold the virgin shall conceive and bear a son” (Is 7:14). With this marriage, then, the tempter of virginity was deceived. For he knew that the coming of the Lord in the flesh would entail the destruction of his dominion.”Basil of Caesarea ,Letter to the Ephesians 19, 1; PG 5, 660 A.
Gambero, L., 1999. Mary and the Fathers of the Church 1st ed. Translated by Buffer, T., San Francisco: Ignatius Press. p. 147.