The Song Of The Harpers By The Glassy Sea. Chapter from “Memories Of Patmos” (A devotional meditation on the book of Revelation) by John MacDuff (1818-1895) 10 pages. ...the sea of glass, as they proclaim, amid all convulsions and all changes, the sway alike of a God of Providence and Grace, and exhort us to sing with them, even now, what will form the theme and anthem of eternity, "The Song of Moses, the servant of God, and the song of the LAMB!"