To me was given the grace to preach the inscrutable riches of Christ. The Church honors today the memory of St. Ambrose of Milan. Among the many things for which St. Ambrose is renowned and remembered, perhaps the one that tops the list is the role he played in the conversion of St. Augustine of Hippo whom he not only baptized but also mentored. He was both a ‘pastor’ and teacher to St. Augustine. However, this is not to say that it is St. Augustine who propelled St. Ambrose to fame. Even before St. Augustine came into the picture, St. Ambrose had already built a name for himself. He was chosen by popular acclaim as the bishop of Milan while he was still a catechumen. As the bishop of Milan, St. Ambrose distinguished himself as a compelling preacher and defender of orthodoxy against Arianism. Along with Saints Jerome, Augustine and Gregory I, Ambrose is one of the four great doctors of the Latin Church. 
In the First Reading, St. Paul is letting the Ephesians know that his own unmerited call to preach to, and boldly evangelize the Gentiles, is a highpoint in a much larger mysterious plan of God. This plan is the coming to knowledge of God by the Gentiles. Whereas St. Ambrose cannot claim to be St. Paul by any means, he too was able to play a part in the continued unveiling of God’s plan to the nations. He accomplished this both as a preacher and a bishop. His dedication as a preacher led to conversion to faith of many souls, including bringing Emperor Theodosius to public penance. As a bishop, St. Ambrose understood that it was his responsibility not only to preach the Word but also to ensure that he shepherded to eternal life the flock which the Lord had put under his charge. Like the good shepherd about whom we have read in the Gospel passage, the wellbeing of the flock was Ambrose’s priority. It was for this reason that he fiercely fought the heretical teaching of Arianism which was leading many people to stray from the faith. 
Whereas all of us cannot become bishops or great doctors of the Church, as the baptized, we are called to be preachers of the Good News. Like St. Ambrose, we too have been given the commission to win over souls for the Lord. Through the intercession of St. Ambrose, may we remain zealous in teaching the true doctrine of our Lord Jesus Christ. May we be able to find our own “Augustines” and help them find their way to God.