Thomas Aquinas

510. Second, he designates the devastator. And first, as to the condition of their leader: in infidelity. Cyrus, he that is unfaithful, that is, unfaithful to his lord Baltasar, rebelling, and besieging Babylon, trusting in his effeminacy, deals unfaithfully, that is, he will deal unfaithfully, seeing that the city cannot be taken by force, fraudulently making peace and commanding homage to the king of Babylon. …

Commentary on Isaiah ↗