on Mary, the Ark of the New Covenant

Gregory Thaumaturgus 1st homily on the Annuciation (213-275 ad)
Come, then, ye too, dearly beloved, and let us chant the melody which has been taught us by the inspired harp of David, and say, "Arise, O Lord, into Thy rest; Thou, and the ark of Thy sanctuary." For the holy Virgin is in truth an ark, wrought with gold both within and without, that has received the whole treasury of the sanctuary.