Gregory Johnson wrote this here:
Though the fact may surprise some who frame the debate in terms of divine sovereignty, it must be stated that Augustine is not an enemy of the free will. In fact, Augustine is vehement in his defense of free will on occasion. In one of his earliest writings, On Free Will, Augustine argues for human free will over against the Manichees among whom he had once been numbered. And as his debates with the Pelagians over election flared up later in life, Augustine was equally forceful in asserting both the freedom of the will and the resulting human responsibility. It was for this reason that Augustine wrote On Grace and Free Will only one year before his primary work on election, On the Predestination of the Saints. Every man has the ability to choose that which he desires; every man has free will.
Augustine was accused by some of changing his position on free will from his earlier work, but Augustine claimed that no change in his thinking took place. Pelagius himself at times quoted from Augustine's On Free Will as an authority to defend his views. By proof-texting Augustine's affirmation of the free will in this earlier writing, the Pelagians argued that Augustine had originally held to a doctrine of the will's moral ability to believe apart from grace, as did they themselves. Augustine rejects this argument. In his Retractiones, Augustine insists that his earlier work On Free Will was simply not concerned with predestination, but with anthropology over against the Manichees. For Augustine, the two debates can be distinct, for, unlike Pelagius, Augustine does not see election as a debate about God's sovereignty or man's natural freedom to choose. The will is not the center of the debate as Augustine frames it; the necessity of God's grace within the individual's experience is central.
I am convinced that heretics like Calvin had great graces but became stuck on the point of predestination, which is easy to do. When one looks at goodness and evil, one must always come back to the Teachings of the Church in humility and frankness. Doctrine trumps experience if there is a problem of understanding. We can come to understanding through experience, but conforming our minds to Christ through the Church opens the door to that understanding. Again, we go to Augustine and one of my favourite theologians, St. Anselm.
Here is Augustine: crede, ut intelligas, "believe so that you may understand"; Tract. Ev. Jo., 29.6. I wish I had one huge library of all Augustine's works and those of Aquinas. Sigh, would be a large library room for sure.............
We need to come to understanding, as much as possible, in order to make our Faith that of an adult and not merely an obedient, albeit, good, child.
Here is Anselm:
I do not endeavor, Lord, to penetrate Thy heights, for in no wise do I compare my understanding with Thine; but I long to understand in some degree Thy truth which my heart believes and loves. For I do not seek to understand in order that I may believe, but I believe in order to understand. For this also I believe-that unless I believe I shall not understand. Prosologion
("faith seeking understanding" or " fides quaerens intellectum")
The mystery of will and grace, understanding and belief forms much of the thought of Augustine and Anselm. But, we also have Thomas on Augustine here from Garrigou-Lagrange:
This principle of predilection presupposes, according to St. Thomas, a decree of the divine will rendering our salutary acts intrinsically efficacious (Ia, q. 19, a. 8). For, if they were efficacious on account of our foreseen consent, of two men equally loved and helped by God, one would be better in some respect. He would be better of himself alone and not on account of divine predilection. But this principle must be reconciled with another which ought to be maintained with equal firmness: “God does not command the impossible, but He teaches thee by commanding to do what thou canst and to ask what thou canst not, and He helps thee that thou mayest be able” (St. Augustine, De natura et gratia, chap. 43, no. 50, and the Council of Trent, Denz., no. 804). Herein lies a great mystery of reconciliation between infinite mercy, infinite justice, and supreme liberty. They are indeed reconciled in the intimate life of the Deity, but of Deity as such we have no positive or proper conception: “Deity is above being, above unity, which are contained in it formally and eminently.” (Cf. Revue thomiste, May-June, 1937, the author’s article, “Le fondement suprême de la distinction des deux grâces suffisante et efficace.”)1 These conclusions from the treatise on God are, then, presupposed in the present discussion.