Andrew of Caesarea
Verses 2-3. The sound of many waters, of thunder, and of those playing on harps indicates the sonority and clarity of the saints' hymns. It also indicates the order, beauty, and harmony of their song, which resounds through the whole Church and the assembly of the firstborn written in heaven. Like the harmony of strings, it agrees with the saints' unanimity in putting bodily passions to death. No one can learn this song except them. For our knowledge itself conforms to the character of our life, just as among human servants the knowledge of their masters' secrets corresponds to the masters' disposition and love toward them.