St. Gregory the Great- why is/was he so great?

St. Gregory the Great: Pope, Confessor and Doctor of the Church

St. Gregory was born in Rome around the year 540, he was the son of Gordianus.  For a time he was a wealthy senator who would later renounce the world and become one of the seven deacons of Rome.  In 574 the Emperor Justine the Younger appointed him 'Chief Magistrate' of Rome, though he was only thirty-four years old at the time.

After the death of his father, he built six monasteries in Sicily and founded a seventh in his own house in Rome where he had grown up.  This monastery was the Benedictine Monastery of St. Andrew where he himself assumed the monastic habit in 575.

After the death of Pelaguis, St. Gregory was chosen Pope by the unanimous consent of priests and people.  Now began those labors which have merited for him the title of "Great".  Hi zeal extended over the entire world, he was in contact with all the Churches of Christendom and, in spite of his bodily sufferings and innumerable labors, he found time to compose a great number of works.  He is known above all for his magnificent contributions to the liturgy of the Mass and Office.  He is one of the great Doctors of the Latin Church.  He died on March 12, 604 (March 12 used to be his Feast Day).

A prayer to St. Gregory the Great...

O God, You who have given to the soul of Your servant Gregory the rewards of everlasting bliss, mercifully grant that we who are oppressed by the weight of our sins, may be relieved by his intercession with You.  Amen.

Source: "Lives of the Saints: for every day of the year" by Rev. Hugo Hoever, S.O.Cist, Ph.D.
Catholic Book Publishing June 1, 1955
NIHIL OBSTAT: John M. Fearns, S.T.D. - Censor Librorum
IMPRIMATUR: Francis Cardinal Spellman, Archbishop of New York