He was born into an ancient noble family. His father, Ambrosius, ruled the present territories of France, Britain, Spain and part of Africa. He was well educated in law and was appointed by Emperor Valentinian as Governor of Liguria and Aemilia with residence in Milan.

When the Bishop of Milan, Auxentius, died in 374, Ambrose came to Milan to insure order and peace. So popular and loved was Ambrose, that the crowds shouted out "Ambrose, Bishop.'' At the time, he was only a catechumen or a beginner in the faith. At the age of 35, he was baptized and ordained a priest and on December 7, 374 A.D., he was consecrated Bishop of Milan. Thus, December 7 is the feast of St. Ambrose in the church calendar.

He immediately divested himself of all his worldly goods and gave over all his personal property to the poor. He became famous for his piety and spirituality and as an eloquent preacher of Catholic doctrine. He was a great orator who attracted thousands to his sermons. Among them was a young man living a dissolute life, St. Augustine.

St. Ambrose was famous for his writings for which he receives the title "Doctor or Teacher of the Church.'' He wrote more than six large volumes covering almost all facets of Christian Dogma. At an earlier date, he wrote the book "On Penance'' which gave evidence of the power of the church to forgive sins, the necessity of Confession and the meritorious character of good works. So well respected was St. Ambrose that he was even able to make the Emperor Theodosius do pubic penance for the massacre of 7000 insurgents before he was admitted into the church for worship. St. Ambrose was the originator of chant in the music of the church and he introduced the responsorial psalms between the readings. He wrote many hymns. Two of the most famous are "Veni, Creator Spiritus" or "Come, Holy Ghost" and the "Te Deum Laudamus" or "We Praise Thee O God."

St. Ambrose died on Good Friday in the year 397. One of St. Ambrose's successors as Bishop of Milan is Pope Paul VI who was Archbishop of Milan before being elected the Bishop of Rome and head of the Universal Church.