21 “He has blessed your children within you.” Who? He “who has set peace as your borders.” How ye all exult! Love peace, my brethren. Greatly are we delighted, when the love of peace cries from your hearts. How greatly does it delight you! I had said nothing: I had explained nothing: I but read the verse, and you shouted. What was it that shouted in you? The love of peace....children of the kingdom, O citizens of Jerusalem, in Jerusalem is the vision of peace: and all who love peace are blest in her, and they enter in, when the doors are being shut, and the bars made strong. This, which when but named ye so love and esteem, this follow after, this long for: this love in your home, in your business, in your wives, in your sons, in your slaves, in your friends, in your enemies....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)