Gregory returned to Rome, and, Pelagius being dead of a plague, he was unanimously chosen Pope. This honour he refused as long as he could. He disguised himself and took refuge in a cave, but was betrayed by a fiery pillar. Being discovered and overruled, he was consecrated at the grave of St. Peter. He left behind him many ensamples of doctrine and holiness to them that have followed him in the Popedom. Every day he brought pilgrims to his table, and among them he entertained not an Angel only, but the very Lord of Angels in the guise of a pilgrim. He tenderly cared for the poor, of whom he kept a list, as well without as within the city. He restored the Catholic faith in many places where it had been overthrown. He fought successfully against the Donatists in Africa and the Arians in Spain. He cleansed Alexandria of the Agnoites. He refused to give the Pall to Syagrius, Bishop of Autun, unless he would expel the Neophyte heretics from Gaul. He caused the Goths to abandon the Arian heresy. He sent into Britain Augustine and divers other learned and holy monks, who brought the inhabitants of that island to believe in Jesus Christ. Hence Gregory is justly called by Bede, the Priest of Jarrow, the Apostle of England. He rebuked the presumption of John, Patriarch of Constantinople, who had taken to himself the title of Bishop of the Universal Church, and he dissuaded the Emperor Maurice from forbidding soldiers to become monks.
Gregory adorned the Church with holy customs and laws. He called together a Synod in the Church of St. Peter, and therein ordained many things; among others, the ninefold repetition of the words Kyrie eleison in the Mass, the saying of the word Alleluia in the Church service except between Septuagesima inclusive and Easter exclusive, and the addition to the Canon of the Mass of the words: Do thou order all our days in thy peace. He increased the Litanies, the number of the Churches where is held the observance called a Station, and the length of the Church Service. He would that the four Councils of Nice, Constantinople, Ephesus, and Chalcedon should be honoured like four Gospels. He released the Sicilian Bishop from visiting Rome every three years, willing them to come instead once every five years. He was the author of many books, and Peter the Deacon declareth that he often saw the Holy Ghost on his head in the form of a dove when he was dictating them. It is a marvel how much he spoke, did, wrote, and legislated, suffering all the while from a weak and sickly body. He worked many miracles. At last God called him away to be blessed for ever in heaven, in the thirteenth year, sixth month, and tenth day of his Pontificate, being the 12th day of March. This day is observed by the Greeks, as well as by the Western Church, as a festival, on account of the eminent wisdom and holiness of this Pope. His body was buried in the Church of St. Peter, hard by the Private Chapel.