For hold this fast as a firm and settled truth, if you would continue Catholics, that God the Father begot God the Son without time, and made Him of a Virgin in time. The first nativity exceeds times; the second nativity enlightens times. Yet both nativities are marvelous; the one without a mother, the other without a father. When God begot the Son, He begot Him of Himself, not of a mother; when the Mother gave birth to her Son, she gave Him birth as a Virgin, not by man. He was born of the Father without a beginning; He was born of a mother, as today at an appointed beginning. Born of the Father He made us; born of a mother He re-made us. He was born of the Father, that we might be; He was born of a mother, that we might not be lost.
-- St. Augustine of Hippo, Sermon 90 on the New Testament, Section 2