The Middle Ages in the West saw the gradual dominance of the Roman rite over the local rites that had developed before the ninth and tenth centuries. Musically this entailed the spread of Gregorian chant. Later centuries saw the development of polyphony. In the late Middle Ages, the preaching service of Prone became the model for Reformed worship.
In the late medieval era, a renewed concern for the inner life emerged. This new kind of mysticism affected the medieval sermon. Mystic John Tauler did not completely abandon the scholastic rules for preaching, but he did alter them freely. It may be said that he practiced a devotional style of preaching.
Gregory, the first monk to sit on the papal chair, marked the transition from the ancient to the medieval. Appreciative of the old, he preserved orthodoxy while instituting changes that carried the Church forward. He also launched missionary campaigns to unreached barbarians north of the old frontier.