Chapter X.
David promises to confess to God in song on the harp: the occasion on which the harp is related to our body, and what kind of sound is fitting for it, is explained.
36. I will praise you with the lyre, my God (Ps. 42:4). Our soul has its lyre. For Paul would not have said, 'I will pray with the spirit, I will pray also with the mind; I will sing with the spirit, I will sing also with the mind' (1 Cor. 14:15), unless he had a lyre that would resound with the plectrum of the Holy Spirit. Our flesh is the lyre when it dies to sin in order to live for God; the lyre is our flesh when it receives the sevenfold Spirit in the sacrament of baptism. For when the turtle is alive, it is engulfed in mud; but when it is dead, its shell is fitted for the purpose of singing, and it speaks in seven different voices, uttering sounds modulated by numbers. Likewise, if our flesh lives for the sake of bodily pleasures, it lives in a certain mire and pit of indulgence. But if it dies to luxury and self-indulgence, then it resumes true life, then it begins to produce the sweet harmony of good deeds. Sweet is the sound of chastity: sweet is the sound of praising God: finally, their sound went out into all the earth (Psalm 19:4); sweet is the sound of the faith which is announced, as it is written (Romans 1:8), in the whole world. May this sound go forth from us to God, as it also went forth from the Thessalonians (1 Thessalonians 1:8); so that we may sing, even without singing, and proclaim the Lord with the harmony of good works, to whom be honor, glory, perpetuity from age to age, now and always and forever and ever. Amen.
Book Three. The Interrogation of Job\.