Legend claims the St. Gregory the Great (d. 604) listened to the first 3 lines chanted by angels on a particular Easter early morning in Rome even though he walked barefoot in a great spiritual procession and that the saint thereupon additional the fourth line: “Ora Professional nobis Deum. Alleluia.” https://vitapronobis57532.oblogation.com/30591926/the-5-second-trick-for-vita-pro-nobis