12 “Peace be in your strength”. O Jerusalem, O city, who art being built as a city, whose partaking is in “The Same:” “Peace be in your strength:” peace be in your love; for your strength is your love. Hear the Song of songs: “Love is strong as death.” A great saying that, brethren, “Love is strong as death.” The strength of charity could not be expressed in grander terms than these, “Love is strong as death.” For who resists death, my brethren? Consider, my brethren. Fire, waves, the sword, are resisted: we resist principalities, we resist kings; death comes alone, who resists it? There is nought more powerful than it. Charity therefore is compared with its strength, in the words, “Love is strong as death.” And since this love slays what we have been, that we may be what we were not; love creates a sort of death in us. This death he had died who said, “The world is crucified unto me, and I unto the world:” this death they had died unto whom he said, “You are dead, and your life is hid with Christ in God.” Love is strong as death...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)