Augustine of Hippo, On the Creed Chapter 6

6. But this Only Son of God, the Father Almighty, let us see what He did for us, what He suffered for us. “Born of the Holy Ghost and of the Virgin Mary.” He, so great God, equal with the Father, born of the Holy Ghost and of the Virgin Mary, born lowly, that thereby He might heal the proud. Man exalted himself and fell; God humbled Himself and raised him up. Christ’s lowliness, what is it? God hath stretched out an hand to man laid low. We fell, He descended: we lay low, He stooped. Let us lay hold and rise, that we fall not into punishment. So then His stooping to us is this, “Born of the Holy Ghost and of the Virgin Mary.” His very Nativity too as man, it is lowly, and it is lofty. Whence lowly? That as man He was born of men. Whence lofty? That He was born of a virgin. A virgin conceived, a virgin bore, and after the birth was a virgin still.