Legend states the St. Gregory The nice (d. 604) listened to the first a few strains chanted by angels on a specific Easter early morning in Rome even though he walked barefoot in a terrific spiritual procession and the saint thereupon added the fourth line: “Ora Professional nobis Deum. Alleluia.” https://vitapronobis09764.onesmablog.com/a-simple-key-for-vita-pro-nobis-unveiled-71619971