How does the Augustinian view of salvation preserve the gratuitousness of grace and salvation against St John Cassian and St Vincent of Lerins? Doesn't a gift ordinarily require that it be received? If we give against, or without regard to, or forcing the consent of, another's freedom to receive, don't we talk about these gifts as gifts in a qualified way? A gift requires that it be received.
This is, I think, where I have to disagree with St. Prosper of Aquitaine, and others who make the assumption that the gratuitousness of divine grace absolutely requires that man have no role whatsoever in actually receiving this grace. Does a tilled field compel the sky to bestow rain, or generate seed on its own? --but they are necessary for the proper reception of these gifts, and do not contribute to the work of the rain and the seeds, they do not "add something" to these gifts: they are merely the proper preparation and reception. The Lord makes our cups overflow: but we must have these earthen vessels poised to receive what He pours. A cracked cup must be patched up before it can hold any liquid for long: patching it does not contribute to the gift of what is poured out, but simply receives it properly. The Giver of Wine may very well likely continue to fill the flask: that does not mean we are receiving properly. And if we do receive properly, that does not mean that we earned it. It just has to do with receiving a gift fittingly, in a manner "meet and right."
I'm only in the Introduction of The Call of All Nations, but the Translator's summary is what the above is in reply to (all parenthetical numbers refer to the chapters of Book 1 of this work):
God wills all men to be saved. Yet many are not saved and do not receive the grace that actually saves. Why? (1). From the threefold degree of man's will, animal, natural, and spiritual, it appears that all initiative for good comes from grace (2-8). But the universal salvific will as taught in Scripture can be understood in the sense of a specified or restricted totality (9-12); the mysterious reason of its restriction remains unknown to us (13f). Saving grace, however, is wholly gratuitous (15), as is clear in the case of children dying before the age of reason (16) and from death-bed conversions (17). It is given without any preceding merit (18) or any effective initiative of nature for good (19). Yet there is a divine salvific will for all (20), though the reason why God chose Israel and left aside the Gentiles, remains a mystery (21) This, however, is certain: the chosen ones are chosen without any merit of their own (22), for all gifts of grace are totally gratuitous (23f.). Why they are given to one and not to another is a mystery which we cannot fathom (25).
What, then, is the answer of Book One to the first aspect of the problem: how is it that, in spite of God's universal salvific will, not all men are saved? Because they do not all receive the grace that actually saves. For this, however, no one can rightly blame God, since grace is a gratuitous gift. We cannot know why it is given to some and not to some others.
I don't like this dodge that poses as an answer, this "we cannot fathom the mind of God" dance. That's not answering the question: the question has to do with the coherence of propositions, and then the muddy connections and the bad assumptions are excused by an appeal to what is legitimately true (i.e., that the Mind of God is unfathomable). If you question these rhetorical tactics, you volunteer to play their game, and so they will accuse you of effectively making an assault on heaven by purportedly saying that God's Mind is in fact fathomable, which is not at all what our objection is.