Complete Extant Works of Saint Ambrose, Vol. I

Furthermore, the rules of piety which he had received from the great bishop, he observed also when he returned later to Constantinople. For when a certain feast day brought him to the Church again, he left immediately after offering his gifts at the sacred table. And when Nectarius, the bishop of that church, asked why he had not remained inside, he sighed and replied:

I have finally and with difficulty been taught what the difference is between a priest and a prince; I have finally and with difficulty found a teacher of truth; for I know only one Ambrose, who deserves to be called a bishop. Such utility resides in a rebuke made by a man endowed with excellent virtue! (Theodoret, Book 5, ch. 18)

In the year 390, when the people of Thessalonica had rebelled during the circus games, Theodosius, driven by fury, ordered the populace to be slaughtered indiscriminately by the sword, to the number of seven thousand; upon hearing this, the bishops gathered in Milan groaned; Ambrose groaned first of all. Nevertheless, he did not want to approach Theodosius immediately, reserving a time for grief for himself and a place for repentance for the prince. Therefore, as Theodosius returned to Milan, the holy bishop withdrew from the city for some days, writing letters to him with his own hand: