Anti-pelagian Writings by St. Augustine
Chapter 2 [II.]--He Proves the Existence of Free Will in Man from the Precepts Addressed to Him by God.
Now He has revealed to us, through His Holy Scriptures, that there is in a man a free choice of will. But how He has revealed this I do not recount in human language, but in divine. There is, to begin with, the fact that God's precepts themselves would be of no use to a man unless he had free choice of will, so that by performing them he might obtain the promised rewards. For they are given that no one might be able to plead the excuse of ignorance, as the Lord says concerning the Jews in the gospel: |If I had not come and spoken unto them, they would not have sin; but now they have no excuse for their sin.| Of what sin does He speak but of that great one which He foreknew, while speaking thus, that they would make their own -- that is, the death they were going to inflict upon Him? For they did not have |no sin| before Christ came to them in the flesh. The apostle also says: |The wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who hold back the truth in unrighteousness; because that which may be known of God is manifest in them; for God hath showed it unto them. For the invisible things of Him are from the creation of the world clearly seen -- being understood by the things that are made -- even His eternal power and Godhead, so that they are inexcusable.| In what sense does he pronounce them to be |inexcusable,| except with reference to such excuse as human pride is apt to allege in such words as, |If I had only known, I would have done it; did I not fail to do it because I was ignorant of it?| or, |I would do it if I knew how; but I do not know, therefore I do not do it|? All such excuse is removed from them when the precept is given them, or the knowledge is made manifest to them how to avoid sin.