How many people could you and I turn to in Faith with our lives? Take a moment and think about it; try to put some names to it. Try to think of someone who has told you that you changed their lives and/or deepened their Faith.
This is not just an idle speculation or mind experiment. Ambrose, in addition to all of his other accomplishments and capabilities, managed to impress Augustine when no other catholic Christians - even his mother, mind you - did not.
Ambrose pray for us that we too might have the grace to live lives of holiness so that "...your light must shine before others, that they may see your good deeds and glorify your heavenly Father." (Matthew. 5:16)
As the Apostle says: "Your life is hidden with Christ in God." (Colossians 3:3) Let, then, no one here strive to shine, let none show pride, let none boast. Christ willed not to be known here, He would not that His Name should be preached in the Gospel while He lived on earth. He came to lie hidden from this world. Let us therefore likewise hide our life after the example of Christ, let us shun boastfulness, let us not desire to be made known. It is better to live here in humility, and there in glory. "When Christ," it says, "shall appear, then shall we also appear with Him in glory." (Colossians 3:4)
-- On the Duties of the Clergy (Book III, 36)