Jerome : (Vers. 23) Praise, O heavens, for the Lord has shown mercy: rejoice, O ends of the earth, let the mountains resound with praise, the forests and every tree in it: for the Lord has redeemed Jacob, and Israel will be glorified. LXX: Rejoice, heavens, for the God of Israel has shown mercy. Sound the trumpet, foundations of the earth, cry out, mountains, with joy: hills and all the trees in them, for God has redeemed Jacob: and Israel will be glorious. If you do this, know that in your salvation, the heavens and the earth will rejoice, and all the elements will harmonize. Whether it be the angels who reside in the heavens, and other powers that support the foundations of the earth. Or certainly the Apostles and Prophets, of whom the Apostle spoke: 'Built upon the foundation of the Apostles and Prophets' (Ephes. II, 20). The mountains and forests, or hills, which, for the variety of their virtues, possessed the first and middle and last places, are commanded to rejoice and sound the trumpet, knowing that the Lord has redeemed Jacob, and in Israel there is joy in the conversion, or that Israel himself, having turned from error, may become illustrious. — Commentary on Isaiah Procopius of Gaza : He calls "depths" what he once called "mountains." They excel in works and words.… For there is a great difference between grace and the law, since the law threatens punishments to those who transgress and calls out a command for repentance. Yet these heralds of grace, rejoicing, cry out proclaiming to the world the forgiveness of sins and justification by faith and the imparting of the Holy Spirit and the radiance of sonship [adoption], as well as the kingdom of heaven and the hope which will not pass away—good things beyond imagining.…The heralds of grace rejoice because Israel has been redeemed and the Son of God glorified. He is their kinsman by nature yet truly God. This moves the earth and its parts to praise. God, who has redeemed Jacob and Israel, will be glorified, or, as in the other translations, "He will be glorified in Israel." — COMMENTARY ON Isaiah 44:6-23 Theodoret of Cyrus : Again, the prophetic text has made use of a personification. Just as when [Isaiah] accuses Israel, he has invited the heavens and the earth to serve as witness, so also when he announces benefits, he invites creation anew to partake in the joy; it is not as though the elements are animate, but when we are depressed, they seem somber to us, and when we are happy, they naturally seem more radiant. It is not the elements that have changed, but it is to us that they present this appearance. If, however, one desires to apprehend the celestial powers by the phrase "the heavens" and the holy prophets by "the foundations of the earth," with the thought that they are the ones who sustain [the benefits], one will not be far from the truth. For the Lord has said, "There is joy in the presence of the angels of God over one sinner who repents." One can understand the mountains, hills and the woods in a similar fashion. After the return of Israel, they flourished again because they were cultivated and were the source of rejoicing on the mountains. — COMMENTARY ON Isaiah 14:44.23