Come, then, let us observe the feast. Come, and we shall commemorate the solemn festival. It is a strange manner of celebrating a festival; but truly wondrous is the whole chronicle of the nativity. For this day the ancient slavery is ended, the devil confounded, the demons take to flight, the power of death is broken, paradise is unlocked, the curse is taken away, sin is removed from us, error driven out, truth has been brought back, the speech of kindliness diffused, and spreads on every side, a heavenly way of life has been implanted on the earth, angels communicate with men without fear, and men now hold speech with angels.
Why is this? Because God is now on earth, and man in heaven; on every side all things commingle. He has come on earth, while being whole in heaven; and while complete in heaven, He is without diminution on earth. Though He was God, He became man; not denying Himself to be God. Though being the impassable Word, He became flesh; that He might dwell amongst us. He became flesh. He did not become God. He was God. Wherefore He became flesh, so that He whom heaven did not contain, a manger would this day receive. He was placed in a manger, so that He, by whom all things are nourished, may receive an infant’s food from his virgin mother. So, the father of all ages, as an infant at the breast, nestles in the virginal arms, that the magi may more easily see Him.
—John Chrysostom (4th Century A.D.)