Jerome

On that day the Lord will visit with His hard, great, and strong sword Leviathan, the twisted serpent, and Leviathan, the fleeing serpent, and He will slay the sea monster that is in the sea. LXX: On that day God will bring forth His holy, great, and strong sword against the fleeing dragon, against the twisted dragon, and He will slay the dragon that is in the sea. The Hebrews understand the devil, that is, the accuser, whose Greek name is Satan (), to be called in Hebrew Satan (), which means adversary. …

Commentary on Isaiah ↗

Gregory the Dialogist

For "Leviathan" is interpreted to be "their addition." Whose "addition," then, but the "addition" of people? And it is properly styled "their addition," for since by his evil suggestion he brought into the world the first sin, he never ceases to add to it day by day by prompting to worse things.Or indeed it is in reproach that he is called Leviathan, that is, styled "the addition of men." For he found them immortal in Paradise, but by promising the divine nature to immortal beings, he as it were pledged himself to add somewhat to …

Morals on the Book of Job, Book 4, Sections 15-16 ↗

Thomas Aquinas

620. In that day. In this part he recalls divine and paternal correction, and first, by foreign scourges, second, by their own scourges: in that day (Isa 27:2); hence it said in Wisdom 11:11: for you didst admonish and try them as a father. Concerning the first, he sets out the scourge of Babylon: with his sword, namely, vengeance; Leviathan, namely, Nabuchodonosor, because of the addition to his kingdom that he subjugated to himself; the serpent, because of his poisonous tyranny; bar, because of the correction of the people by God, …

Commentary on Isaiah ↗