Psalms 74:13

Perhaps my Savior becomes a roe according to contemplation (θεωρία), a hart according to works. And what are these works? He himself slays serpents, when he cuts the throats of the opposing powers. Therefore I will say to him: You have crushed the heads of the dragons upon the water.

Now therefore, O Asaph, amend yourself according to your understanding, tell us what sort of Salvation God has wrought in the midst of the earth. When that earthly Salvation of yours was overthrown, what did He do, what did He promise? "You confirmed in Your virtue the sea" [Psalm 74:13]. As though the nation of the Jews were as it were dry land severed from the waves, the Gentiles in their bitterness were the sea, and on all sides they washed about that land: behold, "You have confirmed in Your virtue the sea," and the land remained thirsting for Your rain. "You have confirmed in Your virtue the sea, You have broken in pieces the heads of dragons in the water." Dragons' heads, that is, demons' pride, wherewith the Gentiles were possessed, You have broken in pieces upon the water: for those persons whom they were possessing, You by Baptism have delivered.

[Daniel 7:2-3] "And during the night I saw in my vision, and behold, the four winds of heaven strove upon the great sea, and four great beasts were coming up out of the sea, differing from one another." The four winds of heaven I suppose to have been angelic powers to whom the principalities have been committed, in accordance with what we read in Deuteronomy: "When the Most High divided the nations and when He separated the children of Adam, He established the bounds of the peoples according to the number of the angels. For the Lord's portion is His people; Jacob is the line of His inheritance (Deuteronomy 32:8). But the sea signifies this world and the present age, overwhelmed with salty and bitter waves, in accordance with the Lord's own interpretation of the dragnet cast into the sea (Matthew 13:47-50). Hence also the sovereign of all creatures that inhabit the waters is described as a dragon, and his heads, according to David, are smitten in the sea (Psalm 74:13). And in Amos we read: "If he descends to the very depth of the sea, there will I give him over to the dragon and he shall bite him" (Amos 9:3). But as for the four beasts who came up out of the sea and were differentiated from one another, we may identify them from the angel's discourse. "These four great beasts," he says, "are four kingdoms which shall rise up from the earth." And as for the four winds which strove in the great sea, they are called winds of heaven because each one of the angels does for his realm the duty entrusted to him. This too should be noted, that the fierceness and cruelty of the kingdoms concerned are indicated by the term "beasts."