StGregoryTheGreat.MasterTheodoric.541 Published March 12, 2010 at 541 × 600 in Morning Prayer 3.12.10, Gregory the Great, Bishop of Rome, 804 Master Theodoric: Gregory the Great. Master Theodoric: Gregory the Great. He did not create the Gregorian chanting style, but it did arise from his systematic liturgical reforms – just one of the achievements that earned him the title of Great.