16 But in order that we may attain, if we cannot yet see God the Word, let us hear the Word made Flesh; seeing we are carnal, let us hear the Word Incarnate. For for this cause came He, for this cause took upon Him our infirmity, that you might be able to receive the strong words of a God bearing your weakness. And He is truly called “milk.” For He gives milk to infants, that He may give the meat of wisdom to them of riper years. Suck then now with patience, that you may be fed to your heart's most eager wish.
For how is even the milk, wherewith infants are suckled, made? Was it not solid meat on the table? But the infant is not strong enough to eat the meat which is on the table; what does the mother do? She turns the meat into the substance of her flesh, and makes milk of it. Makes for us what we may be able to take. So the Word was made Flesh, that we little ones, who were indeed as infants with respect to food, might be nourished by milk. But there is this difference; that when the mother makes the food turned into flesh milk, the food is turned into milk; whereas the Word abiding Itself unchangeably assumed Flesh, that there might be, as it were, a tissue of the two.
What He is, He did not corrupt or change, that in your fashion, He might speak to you, not transformed and turned into man. For abiding unalterable, unchangeable, and altogether inviolable, He became what you are in respect of you, what He is in Himself in respect of the Father.
Source: Sermons on Selected Lessons of the New Testament (New Advent)