Chapter 33 — Part IV: Prayer — On Prayer in General
Section 12. Unwise And Indevout Prayers Unheard — Sometimes, indeed, it happens that what we ask of God we do not obtain. But it is then especially that God looks to our welfare, either because He bestows on us other gifts of higher value and in greater abundance, or because what we ask, far from being necessary or useful, would prove superfluous and injurious. God, says St. Augustine, denies some things in His mercy which He grants in His wrath.