From Augustine’s letter to Jerome (AD 415), as translated and quoted in The Nicene and Post-Nicene Fathers, 1:527–528:
Not in vain has the prophet, taught by divine inspiration, declared concerning God, “He bringeth forth in measured harmonies the course of time” [Isa. 40:26]. For which reason music, the science or capacity of correct harmony, has been given also by the kindness of God to mortals having reasonable souls, with a view to keep them in mind of this great truth. For if a man, when composing a song which is to suit a particular melody, knows how to distribute the length of time allowed to each word so as to make the song flow and pass on in most beautiful adaptation to the ever changing notes of the melody, how much more shall God, whose wisdom is to be esteemed as infinitely transcending human arts, make infallible provision that not one of the spaces of time alloted to natures that are born and die — spaces which are like the words and syllables of the successive epochs of the course of time — shall have, in what we may call the sublime psalm of the vicissitudes of this world, a duration either more brief or more protracted than the foreknown and predetermined harmony requires! For when I may speak thus with reference even to the leaves of every tree, and the number of the hairs upon our heads, how much more may I say it regarding the birth and death of men, seeing that every man’s life on earth continues for a time, which is neither longer nor shorter than God knows to be in harmony with the plan according to which He rules the universe.