Christmas Eve

How is He contained in a womb, whom nothing can contain? And how can He who is in the bosom of the Father be held in the arms of His Mother? This is according to His good pleasure, as He knoweth and wisheth. For being without flesh, of His own will has He been made flesh; and He who is, for our sakes has become that which He was not. Without departing from His own nature He has shared in our substance. Desiring to fill the world on high with citizens, Christ has undergone a twofold birth. (Hymn, Matins of Nativity)