Christ Feeds Us the Milk of His Flesh

For as it certainly is in the power of a mother to give strong food to her infant, but she does not do so, as the child is not yet able to receive more substantial nourishment; so also it was possible for God himself to have made man perfect from the first, but man could not receive this perfection, being as yet an infant.  And for this cause our Lord in these last times, when he had summed up all things into himself, came to us, not as he might have come, but as we were capable of beholding him.  He might easily have come to us in his immortal glory, but in that case we could never have endured the greatness of the glory; and therefore it was that he, who was the perfect bread of the Father, offered himself to us as milk, because we were as infants.  He did this when he appeared as a man, that we, being nourished, as it were, from the breast of his flesh, and having, by such a course of milk nourishment, become accustomed to eat and drink the Word of God, may be able also to contain in ourselves the Bread of immortality, which is the Spirit of the Father.

– from Against Heresies (c. 174–189), Book IV, Chapter 38, by Irenaeus of Lyons