Thee, O God, we praise
Youtube video: https://www.youtube.com/watch?v=xvAoiu6v0h4
This ancient hymn is traditionally attributed to Ambrose and/or Augustine (though Niketas of Remesiana remains a possibility). I believe Luther once said that this ranks right up there with the three creeds in terms of its quality and doctrinal clarity.
The hymn follows the outline of the Apostles' Creed, mixing a poetic vision of the heavenly liturgy with its declaration of faith. Calling on the name of God immediately, the hymn proceeds to name all those who praise and venerate God, from the hierarchy of heavenly creatures to those Christian faithful already in heaven to the Church spread throughout the world. The hymn then returns to its credal formula, naming Christ and recalling his birth, suffering and death, his resurrection and glorification. At this point the hymn turns to the subjects declaiming the praise, both the universal Church and the singer in particular, asking for mercy on past sins, protection from future sin, and the hoped-for reunification with the elect.
See The Lutheran Hymnal, The Order of Matins (p. 35).
The setting used in TLH is really quite nice--dramatic, but not overly so. The arc of the text is reflected in the "journey" between two key areas: Bb major and Bb minor.
Our hymn of praise begin in Bb major ("We praise thee...Thou art the everlasting Son..."), but suddenly shifts to Bb minor, reflecting Christ's sacrificial work ("When thou tookest upon Thee to deliver man...sharpness of death..."), returning to praise and supplication in Bb major ("O Lord save Thy people...O Lord in Thee have I trusted; let me never be confounded.")