10 . . . And you are clean, but not all. 11 For he knew who he was that would betray him; therefore he said: You are not all clean.
Origen: Ye are clean, refers to the eleven; but not all, to Judas. He was unclean, first, because he cared not for the poor, but was a thief; secondly, because the devil had put it into his heart to betray Christ. Christ washes their feet after they are clean, shewing that grace goes beyond necessity, according to the text, He that is holy, let him be holy still [Rev 22:11].
12 Then after he had washed their feet, and taken his garments, being set down again, he said to them: Know you what I have done to you? 13 You call me Master, and Lord; and you say well, for so I am.
Augustine: It is enjoined in the Proverbs, Let another man praise thee, and not thine own mouth [Prov 27:2]. For it is dangerous for one to praise himself, who has to beware of pride. But He who is above all things, howsoever He praise Himself, extolleth not Himself too highly. Nor can God be called arrogant: for that we should know Him is no gain to Him, but to us. Nor can anyone know Him, unless He who knows, shew Himself. So that if to avoid arrogance He did not praise Himself, He would be denying us wisdom. . . . To His calling Himself Master, no one could object, even were He man only, since professors in different arts call themselves so without presumption. But what free man can bear the title of lord in a man? Yet when God speaks, height cannot exalt itself; truth cannot lie; it is for us to submit to that height, to obey that truth.
14 If then I being your Lord and Master, have washed your feet; you also ought to wash one another’s feet. 15 For I have given you an example, that as I have done to you, so you do also.
Chrysostom: He shews us the greater, that we may do the less. For He was the Lord, but we, if we do it, do it to our fellow-servants.
Bede: Our Lord first did a thing, then taught it: as it is said, Jesus began both to do and to teach [Acts 1:1].
Augustine: When the body is bent at the feet of a brother, the feeling of humility is made to rise in the heart, or, if it be there already, is confirmed. But besides this moral meaning, is not a brother able to change a brother from the pollution of sin? Let us confess our faults one to another, forgive one another’s faults, pray for one another’s faults. In this way we shall wash one another’s feet.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. IV (London: Rivington, 1845).