11 Lastly, what have You done in the sea itself, to pacify its rage, and to weaken it? “You have humbled the proud as one that is wounded”. There is a certain proud serpent in the sea, of which another passage of Scripture speaks, “I will command the serpent, and he shall bite him;” and again, “There is that Leviathan, whom You have made to mock him,” whose head He bruises above the water. “You,” he says, “hast humbled the proud, as one that is wounded.” You have humbled Yourself, and the proud was humbled: for the proud held the proud ones through pride: but the great One is humbled, and by believing in Him become small.
While the little one is nourished by the example of One who from greatness descended to humility, the devil has lost what he held: because the proud held only the proud. When such an example of humility was displayed before them, men learned to condemn their own pride, and to imitate the humility of God. Thus also the devil, by losing those whom he had in his power, has even himself been humbled; not chastened, but thrown prostrate. “You have humbled the proud like one that is wounded.”
You have been humbled, and hast humbled others: You have been wounded, and hast wounded others: for Your blood, as it was shed to blot the handwriting of sins, could not but wound him. For what was the ground of his pride, except the bond which he held against us. This bond, this handwriting, You have blotted out with Your blood: him therefore have You wounded, from whom You have rescued so many victims. You must understand the devil wounded, not by the piercing of the flesh, which he has not, but by the bruising of his proud heart. “You have scattered Your enemies abroad with Your mighty arm.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)