How beautiful... — The image is reproduced, with variations, from Isaiah 40:9. There Zion herself was the herald proclaiming the glad tidings; here the heralds are seen coming to Zion, to tell her that her God is verily reigning, and their feet are beautiful on the mountains like those of an antelope (Song of Solomon 2:8-9; Nahum 1:15).
Related Commentaries of Isaiah 52:7
Isaiah 52:7
7 How beautiful upon the mountains are the feet of him that bringeth good tidings, that publisheth peace; that bringeth good tidings of good, that publisheth salvation; that saith unto Zion, Thy God reigneth!