During the Welsh Revivals of the early 20th century, Bible teacher and author G. Campbell Morgan described what he observed. He believed the presence of God’s Holy Spirit was moving on “billowing waves of sacred song.” Morgan wrote that he had seen the unifying influence of music in meetings that encouraged voluntary prayers, confession, and spontaneous singing. If someone got carried away by their feelings and prayed too long, or spoke in a way that didn’t resonate with others, someone would begin to softly sing. Others would gently join in, the chorus swelling in volume until drowning out all other…