Since we are still very much in the Christmas season, it's appropriate to read a bit of one of his Nativity sermons. The citation is Sermo 1 in Nativitate Domini, 1-3: PL 54, 190-193.
Dearly beloved, today our Savior is born; let us rejoice. Sadness should have no place on the birthday of life. The fear of death has been swallowed up; life brings us joy with the promise of eternal happiness.
No one is shut out from this joy; all share the same reason for rejoicing. Our Lord, victor over sin and death, finding no man free from sin, came to free us all. Let the saint rejoice as he sees the palm of victory at hand. Let the sinner be glad as he receives the offer of forgiveness. Let the pagan take courage as he is summoned to life.
In the fullness of time, chosen in the unfathomable depths of God's wisdom, the Son of God took for himself our common humanity in order to reconcile it with its creator. He came to overthrow the devil, the origin of death, in that very nature by which he had overthrown mankind...
Christian, remember your dignity, and now that you share in God's own nature, do not return by sin to your former base condition. Bear in mind who is your head and and of whose body you are a member. Do not forget that you have been rescued from the power of darkness and brought into the light of God's kingdom.