From Commentary on the Psalms 1.4-9 (ca. 490-397)

What is more pleasing than a psalm? David expresses it well: “Praise the Lord, for a song of praise is good: let there be praise of our God with gladness and grace.” Yes, a psalm is a blessing on the lips of the people, a hymn in praise of God, the assembly’s homage, the general exclamation, a word that speaks for all, the voice of the Church, the confession of faith in song. It is the voice of complete assent, the joy of freedom, the cry of happiness, the echo of gladness. It soothes the temper, distracts from care, lightens the burden of sorrow. It is a source of security at night, a lesson in wisdom by day. It is a shield when we are afraid, the celebration of holiness, a vision of serenity, a promise of peace and harmony. It is just like a lyre, evoking harmony from a blend of notes. Day begins to the music of a psalm. Day closes to the echo of a psalm.

In a psalm, instruction vies with beauty. We sing for pleasure. We learn for our profit. What experience is not covered by a reading of the psalms? I come across the words:’ a song for the beloved’, and I am aflame with desire for God’s love. I go through God’s revelation in all its beauty, the intimations of resurrection, the gifts of his promise. I learn to avoid sin. I see my mistake and feeling ashamed of repentance for my sins.

What is a psalm but a musical instrument to give expression to all the virtues? The psalmist of old used it, with the aid of the Holy Spirit, to make earth re-echo the music of heaven. The psalmist used the dead gut of strings to create harmony from a variety of notes, in order to send up to heaven the song of God’s praise. In doing so, the psalmist taught us that we must first die to sin, and then create in our lives on earth a harmony through virtuous deeds, if the grace of our devotion is to reach up to the Lord.

St. Ambrose (ca. 334-397) became Archbishop of Milan at a time of bitter strife about Christological doctrine, and upheld orthodox teaching in a his widely circulated sermons and treatises. He is credited with introducing hymns to the Western Church, some composed by himself, and his greatest disciple was the even more influential St. Augustine. His commentary on twelve psalms, a collection of earlier sermons, was published near the end of his life. His feast day is December 7.