"[Referring to a Psalm]...For by "spontaneous rain" nothing else is meant than grace, not rendered to merit, but given freely, whence also it is called grace; for He gave it, not because we were worthy, but because He willed. And knowing this, we shall not trust in ourselves; and this is to be made "weak." But He Himself makes us perfect, who says also to the Apostle Paul, "My grace is sufficient for you, for my strength is made perfect in weakness." Man, then, was to be persuaded how much God loved us, and what manner of men we were whom He loved; the former, lest we should despair; the latter, lest we should be proud. And this most necessary topic the apostle thus explains: "But God commends," he says, "His love towards us, in that, while we were yet sinners, Christ died for us. Much more then, being now justified by His blood, we shall be saved from wrath through Him. For if, when we were enemies, we were reconciled to God by the death of His Son; much more, being reconciled, we shall be saved by His life." Romans 5:8-10— Donavit Also in another place: "What," he says, "shall we then say to these things? If God be for us, who can be against us? He that spared not His own Son, but delivered Him up for us all, how has He not with Him also freely given us all things?" Now that which is declared to us as already done, was shown also to the ancient righteous as about to be done; that through the same faith they themselves also might be humbled, and so made weak; and might be made weak, and so perfected." - St. Augustine, On the Trinity, Book IV, ch. 1
Nothing particularly polemical here, just a quote I enjoyed.