Basil of Caesarea

For "he did not know her" - it says - "until she gave birth to a Son, her firstborn." But this could make one suppose that Mary, after having offered in all her purity her own service in giving birth to the Lord, by virtue of the Holy Spirit, did not subsequently refrain from normal conjugal relations. That would not have affected the teaching of our religion at all, because Mary's virginity was necessary until the service of the Incarnation, and what happened afterward need not be investigated in order to affect the doctrine of the mystery. But since the lovers of Christ [that is, the faithful] do not allow themselves to hear that the Mother of God ceased at a given moment to be a virgin, we consider their testimony sufficient.