11 O that I may have induced you, my brethren, to give away your earthly bread, and to knock for the heavenly! The Lord is that Bread. He says, “I am the Bread of life.” But how shall He give to you, who givest not to him that is in need? One is in need before you, and you are in need before Another, and since you are in need before Another, and another is in need before you, that other is in need before him who is in need himself. For He before whom you are in need, needs nothing.
Do then to others as you would have done to you. For it is not in this case as with those friends who are wont to upbraid in a way one another with their kindnesses; as, “I did this for you,” and the other answers, “and I this for you,” that He wishes us to do Him some good office, because He has first done such an office for us. He is in want of nothing, and therefore is He the very Lord. I said unto the Lord, “You are my God, for Thou needest not my goods.” Notwithstanding though He be the Lord, and the Very Lord, and needs not our goods, yet that we might do something even for Him, has He vouchsafed to be hungry in His poor.
“I was hungry,” says He, “and you gave Me meat. Lord, when saw we You hungry? Forasmuch as you did it to one of the least of Mine, you did it to Me.” To be brief then, let men hear, and consider as they ought, how great a merit it is to have fed Christ when He hungers, and how great a crime it is to have despised Christ when He hungers.
Source: Sermons on Selected Lessons of the New Testament (New Advent)