Leo the Great here emphasizes that the Incarnation, the mystery of God becoming man, changes everything. Human dignity is now vastly elevated, requiring us to live in a new way, according to our new spiritual nature, with a new relationship to the visible things of this beautiful but passing world.
Our Lord Jesus Christ, born true man without ever ceasing to be true God, began in his person a new creation and by the manner of his birth gave man a spiritual origin.
Recognize your Dignity
What mind can grasp this mystery, what tongue can fittingly recount this gift of love? Guilt becomes innocence, old becomes new, strangers are adopted and outsiders are made heirs. Rouse yourself, man, and recognize the dignity of your nature. Remember that you were made in God’s image; though corrupted in Adam, that image has been restored in Christ.
The Proper Use of Creatures
Use creatures as they should be used: the earth, the sea, the sky, the air, the springs and the rivers. Give praise and glory to their Creator for all that you find beautiful and wonderful in them. See with your bodily eyes the light that shines on earth, but embrace with your whole soul and all your affections the true light which enlightens every man who comes into this world.
Greater in You
Speaking of this light the prophet said: Draw close to him and let his light shine upon you and your face will not blush with shame. If we are indeed the temple of God and if the Spirit of God lives in us, then what every believer has within himself is greater than what he admires in the skies.
Our words and exhortations are not intended to make you disdain God’s works or think there is anything contrary to your faith in creation, for the good God has himself made all things good. What we do ask is that you use reasonably and with moderation all the marvelous creatures which adorn this world; as the Apostle says: The things that are seen are transient but the things that are unseen are eternal.
Be intent upon the Eternal
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 think of how divine grace has transformed our earthly natures so that we may contemplate more closely our heavenly hope. We hear the Apostle say: You are dead and your life is hidden with Christ in God. But when Christ you life appears, then you will also appear in glory with him, who lives and reigns with the Father and the Holy Spirit for ever and ever. Amen.
St. Leo, one of the early Church Fathers, was Pope in the middle of the 5th century and is especially renowned for his preaching on the mystery of the incarnation and its meaning for human dignity. This excerpt from one of his sermons (Sermo 7 in Nativitate Domini, 2.6; PL 54, 217-218, 220-221) appears in the Roman Office of Readings for Friday of the 5th week in ordinary time with the accompanying biblical reading of Galatians 5;1-25.