Legend suggests the St. Gregory The good (d. 604) listened to the very first a few traces chanted by angels on a certain Easter early morning in Rome although he walked barefoot in an excellent religious procession and the saint thereupon additional the fourth line: “Ora Professional nobis Deum. Alleluia.” https://vita-pro-nobis53208.dbblog.net/4479140/5-tips-about-vita-pro-nobis-you-can-use-today