From “Sermon 7: On the Nativity” (ca. 450)
Our Lord Jesus Christ, born truly human without ever ceasing to be true God, was in his own person the prelude of a new creation, and by the manner of his birth he gave humanity a spiritual origin. What mind can grasp this? What tongue can do justice to this gift of love? Guilt becomes innocence, what was old becomes new, strangers are adopted into the family, and outsiders are made heirs
Rouse yourself, therefore, and recognize the dignity of your nature. Remember that you were made in God’s image; and though defaced in Adam, that image has now been restored in Christ. Use this visible creation as it should be used: the earth, the sea, the sky, the air, the springs and rivers. Give praise and glory to their Creator for all that you find beautiful and wonderful in them. See with your bodily eyes the sunlight shining upon the earth, but embrace with your whole soul and all your affections “the true light which enlightens everyone who comes into this world.” Speaking of this light the prophet David in the Psalms says, “Look on him and be radiant; and your face shall never be ashamed.” If we are indeed the temple of God and if the Spirit of God lives in us, then what every believer has within is of greater worth than what we can admire in the skies. …
For we are born in the present only to be reborn in the future. Our attachment, therefore, should not be to the transitory; instead, we must be intent upon the eternal. Let us constantly reflect on how divine grace has transformed our earthly natures so that we may contemplate more closely our heavenly hope. And let us attend to the words of the apostle Paul, “You have died, and your life is hidden with Christ in God. But when Christ your life appears, you also shall appear with him in glory.”
St. Leo the Great (ca. 400-461) was a Roman cleric and theologian. He served as a diplomat for the papal court and became Bishop of Rome in 440, exercising pastoral care during the depredations of the Huns and the Vandals. His Tome, a clear defense of the the teaching that the one person of Christ has two natures, divine and human, was adopted by the Council of Chalcedon as a crucial marker of orthodoxy. His feast day is November 10.