Today (December 7) was the feast of St. Ambrose of Milan, Doctor of the Church. Ambrose was born in Trier, but he was in many ways the most Roman of the Church Fathers, a Roman's Roman, born to a good Roman family, educated in Rome, pursuing a career in Roman law. He became consular prefect of Aemilia-Liguria, which brought him to Milan. When the See of Milan -- one of the most important sees in the West, and closely connected at that time with the imperial court -- fell vacant, there was a big dispute over who should become the next bishop. Ambrose stepped in to keep the argument from getting out of hand -- and the people demanded that he become the bishop. He was only a catechumen, so he was baptized, confirmed, ordained, and installed as bishop of Milan all on the same day, December 7, 374. He gave his property to the Church and started reading theology -- as someone with a good Roman education, he could read Greek as well as Latin, and taught himself what he needed to know with his usual practical efficiency. (It may be that this process of having to do so much studying may have been a reason for his habit of reading silently, which Augustine mentions, although it's also possible that it is a habit he picked up earlier.) He was never one to back down when he thought he was right, and he faced down Emperor Theodosius more than once.
From
Book I, Chapter I of his De fide:
Now this is the declaration of our Faith, that we say that God is One, neither dividing His Son from Him, as do the heathen, nor denying, with the Jews, that He was begotten of the Father before all worlds, and afterwards born of the Virgin; nor yet, like Sabellius, confounding the Father with the Word, and so maintaining that Father and Son are one and the same Person; nor again, as does Photinus, holding that the Son first came into existence in the Virgin's womb: nor believing, with Arius, in a number of diverse Powers, and so, like the benighted heathen, making out more than one God. For it is written: "Hear, O Israel: the Lord your God is one God."
For God and Lord is a name of majesty, a name of power, even as God Himself says: "The Lord is My name," and as in another place the prophet declares: "The Lord Almighty is His name." God is He, therefore, and Lord, either because His rule is over all, or because He beholds all things, and is feared by all, without difference.
If, then, God is One, one is the name, one is the power, of the Trinity. Christ Himself, indeed, says: "Go, baptize the nations in the name of the Father, and of the Son, and of the Holy Spirit." In the name, mark you, not in the names.
