7 But there are some that conspire, that “gather themselves together against the Lord, and against His Christ.” They have come together, they have conspired. “Flash forth Your lightnings, and You shall scatter them.” Abound with Your miracles, and their conspiracy shall be broken....“Send forth Your arrows, and You shall confound them.” Let the unsound be wounded, that, being well wounded, they may be made sound; and let them say, being set now in the Church, in the Body of Christ, let them say with the Church, “I am wounded with Love.” “Send forth Your Hand from on high.”
What afterward? What in the end? How conquers the Body of Christ? By heavenly aid. “For the Lord Himself shall come with the voice of the Archangel, and with the trump of God shall He descend from heaven,” Himself the Saviour of the body, the Hand of God. What is, “Out of many waters”? From many peoples. What peoples? Aliens, unbelievers, whether assailing us from without, or laying snares within. Take me out of many waters, in which You disciplined me, in which You rolled me, to free me from my filth.
This is the “water of contradiction.”...“From the hand of strange children.” Hear, brethren, among whom we are, among whom we live, from whom we long to be delivered. “Whose mouth has spoken vanity”. All of you today, if you had not gathered yourselves together to these divine shows of the word of God, and were not at this hour engaged in them, how great vanities would ye be hearing! “whose mouth has spoken vanity:” when, in short, would they, speaking vanity, hear you speaking vanity?
“And their right hand is a right hand of iniquity.” What doest thou among them with your pastoral scrip with five stones in it? Say it to me in another form: that same law which you have signified by five stones, signify in some other way also. “I will sing a new song unto You, O God”. “A new song” is of grace; “a new song” is of the new man; “a new song” is of the New Testament. But lest you should think that grace departs from the law, whereas rather by grace the law is fulfilled, “upon a psaltery of ten strings will I sing unto You.”
Upon the law of ten commandments: therein may I sing to You; therein may I rejoice to You; therein may “I sing to You a new song;” for, “Love is the fulfilling of the law.” But they who have not love may carry the psaltery, sing they cannot. Contradiction cannot make my psaltery to be silent.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)