1 The title of the Psalm goes thus. “To the end: for the sons of Korah: a Psalm of David himself.” These sons of Korah have the title also of some other Psalms, and indicate a sweet mystery, insinuate a great Sacrament: wherein let us willingly understand ourselves, and let us acknowledge in the title us who hear, and read, and as in a glass set before us behold who we are. The sons of Korah, who are they?...Haply the sons of the Bridegroom. For the Bridegroom was crucified in the place of Calvary. Recollect the Gospel, where they crucified the Lord, and you will find Him crucified in the place of Calvary. Furthermore, they who deride His Cross, by devils, as by beasts, are devoured. For this also a certain Scripture signified. When God's Prophet Elisha was going up, children called after him mocking, “Go up thou bald head, Go up thou bald head:” but he, not so much in cruelty as in mystery, made those children to be devoured by bears out of the wood. If those children had not been devoured, would they have lived even till now? Or could they not, being born mortal, have been taken off by a fever? But so in them had no mystery been shown, whereby posterity might be put in fear. Let none then mock the Cross of Christ. The Jews were possessed by devils, and devoured; for in the place of Calvary, crucifying Christ, and lifting on the Cross, they said as it were with childish sense, not understanding what they said, “Go up, thou bald head.” For what is, “Go up”? “Crucify Him, Crucify Him.” For childhood is set before us to imitate humility, and childhood is set before us to beware of foolishness. To imitate humility, childhood was set before us by the Lord, when He called children to Him, and because they were kept from Him, He said, “Suffer them to come unto Me, for of such is the Kingdom of Heaven.” The example of childhood is set before us to beware of foolishness by the Apostle, “Brethren, be not children in understanding:” and again he proposes it to imitate, “Howbeit in malice be ye children, that in understanding ye may be men.” “For the sons of Korah” the Psalm is sung; for Christians then is it sung. Let us hear it as sons of the Bridegroom, whom senseless children crucified in the place of Calvary. For they earned to be devoured by beasts; we to be crowned by Angels. For we acknowledge the humility of our Lord, and of it are not ashamed. We are not ashamed of Him called in mystery “the bald” (Calvus), from the place of Calvary. For on the very Cross whereon He was insulted, He permitted not our forehead to be bald; for with His own Cross He marked it. Finally, that you may know that these things are said to us, see what is said.
2. “O clap your hands, all you nations”. Were the people of the Jews all the nations? No, but blindness in part is happened to Israel, that senseless children might cry, “Calve,” “Calve;” and so the Lord might be crucified in the place of Calvary, that by His Blood shed He might redeem the Gentiles, and that might be fulfilled which says the Apostle, “Blindness in part is happened unto Israel, until the fullness of the Gentiles be come in.” Let them insult, then, the vain, and foolish, and senseless, and say, “Calve,” “Calve;” but you redeemed by His Blood which was shed in the place of Calvary, say, “O clap your hands, all you nations;” because to you has come down the Grace of God. “O clap your hands.” What is “O clap”? Rejoice. But wherefore with the hands? Because with good works. Do not rejoice with the mouth while idle with the hands. If you rejoice, “clap your hands.” The hands of the nations let Him see, who joys has deigned to give them. What is, the hands of the nations? The acts of them doing good works. “O clap your hands, all you nations: shout unto God with the voice of triumph.” Both with voice and with hands. If with the voice only it is not well, because the hands are slow; if only with the hands it is not well, because the tongue is mute. Agree together must the hands and tongue. Let this confess, these work. “Shout unto God with the voice of triumph.”
3. “For the Lord Most High is terrible”. The Most High in descending made like one ludicrous, by ascending into Heaven is made terrible. “A great King over all the earth.” Not only over the Jews; for over them also He is King. For of them also the Apostles believed and of them many thousands of men sold their goods, and laid the price at the Apostles' feet, and in them was fulfilled what in the title of the Cross was written, “The King of the Jews.” For He is King also of the Jews. But “of the Jews” is little. “O clap your hands, all you nations: for God is the King of all the earth.” For it suffices not Him to have under Him one nation: therefore such great price gave He out of His side, as to buy the whole world.
4. “He has subdued the people under us, and the nations under our feet”. Which subdued, and to whom? Who are they that speak? Haply Jews? Surely, if Apostles; surely, if Saints. For under these God has subdued the people and the nations, that today are they honoured among the nations, who by their own citizens earned to be slain: as their Lord was slain by His citizens, and is honoured among the nations; was crucified by His own, is adored by aliens, but those by a price made His own. For therefore bought He us, that aliens from Him we might not be. Do you think then these are the words of Apostles, “He has subdued the people under us, and the nations under our feet”? I know not. Strange that Apostles should speak so proudly, as to rejoice that the nations were put under their feet, that is, Christians under the feet of Apostles. For they rejoice that we are with them under the feet of Him who died for us. For under Paul's feet ran they, who would be of Paul, to whom He said, “Was Paul crucified for you?” What then here, what are we to understand? “He has subdued the people under us, and the nations under our feet.” All pertaining to Christ's inheritance are among “all the nations,” and all not pertaining to Christ's inheritance are among “all the nations:” and you see so exalted in Christ's Name is Christ's Church, that all not yet believing in Christ lie under the feet of Christians. For what numbers now run to the Church; not yet being Christians, they ask aid of the Church; to be succoured by us temporally they are willing, though eternally to reign with us as yet they are unwilling. When all seek aid of the Church, even they who are not yet in the Church, has He not “subdued the people under us, and the nations under our feet”?
Source: The Enarrations, or Expositions, on the Psalms (New Advent)