Legend suggests the St. Gregory The nice (d. 604) read the initial three strains chanted by angels on a particular Easter morning in Rome when he walked barefoot in an incredible spiritual procession and which the saint thereupon extra the fourth line: “Ora pro nobis Deum. Alleluia.” This Marian hymn https://riverngvni.livebloggs.com/37399966/5-simple-statements-about-vita-pro-nobis-explained