St. GREGORY the GREAT, Pope and Doctor.

Saint GREGORY the GREAT, son of Gordianus, a Roman regionarius, and Saint Silvia of Rome, nephew of Saint Emiliana and Saint Tarsilla, great-grandson of Pope Saint Felix III. Educated by the finest teachers in Rome, he served as prefect of Rome for a year, then he sold his possessions, turned his home into a Benedictine monastery, and used his money to build six monasteries in Sicily and one in Rome. Upon seeing English children being sold in the Roman Forum, he became a missionary to England.

He was elected 64th Pope by unanimous acclamation on 3 September 590, the first monk to be chosen. He sent Saint Augustine [of Canterbury] and a company of monks to evangelize England, as well as other missionaries to France, Spain, and Africa. He collected melodies and plainchant so associated with him that they are now known as Gregorian Chants. One of the four great Doctors of the Latin Church,  he wrote seminal works on the Mass and Divine Office, several of them dictated to his secretary, Saint Peter the Deacon.

(iBreviary)