2 “The earth is the Lord's, and the fullness thereof, the compass of the world, and all they that dwell therein”; when the Lord, being glorified, is announced for the believing of all nations; and the whole compass of the world becomes His Church. “He has founded it above the seas.” He has most firmly established it above all the waves of this world, that they should be subdued by it, and should not hurt it. “And has prepared it above the rivers”. The rivers flow into the sea, and men of lust lapse into the world: these also the Church, which, when worldly lusts have been conquered by the grace of God, has been prepared by love for the reception of immortality, subdues.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)