6 Permit me now, therefore, to bring before you the question which I desire to have solved, and do not reject me; so may He not reject you who condescended to be rejected for our sakes!
I ask where can the soul, even of an infant snatched away by death, have contracted the guilt which, unless the grace of Christ has come to the rescue by that sacrament of baptism which is administered even to infants, involves it in condemnation? I know you are not one of those who have begun of late to utter certain new and absurd opinions, alleging that there is no guilt derived from Adam which is removed by baptism in the case of infants. If I knew that you held this view, or, rather, if I did not know that you reject it, I would certainly neither address this question to you, nor think that it ought to be put to you at all. Since, however, we hold on this subject the opinion consonant with the immoveable Catholic faith, which you have yourself expressed when, refuting the absurd sayings of Jovinian, you have quoted this sentence from the book of Job: “In your sight, no one is clean, not even the infant, whose time of life on earth is a single day,” adding, “for we are held guilty in the similitude of Adam's transgression,” — an opinion which your book on Jonah's prophecy declares in a notable and lucid manner, where you affirm that the little children of Nineveh were justly compelled to fast along with the people, because merely of their original sin, — it is not unsuitable that I should address to you the question— where has the soul contracted the guilt from which, even at that age, it must be delivered by the sacrament of Christian grace?
7. Some years ago, when I wrote certain books concerning Free Will, which have gone forth into the hands of many, and are now in the possession of very many readers, after referring to these four opinions as to the manner of the soul's incarnation—(1) that all other souls are derived from the one which was given to the first man; (2) that for each individual a new soul is made; (3) that souls already in existence somewhere are sent by divine act into the bodies; or (4) glide into them of their own accord, I thought that it was necessary to treat them in such a way that, whichever of them might be true, the decision should not hinder the object which I had in view when contending with all my might against those who attempt to lay upon God the blame of a nature endowed with its own principle of evil, namely, the Manichæans; for at that time I had not heard of the Priscillianists, who utter blasphemies not very dissimilar to these. As to the fifth opinion, namely, that the soul is a part of God—an opinion which, in order to omit none, you have mentioned along with the rest in your letter to Marcellinus (a man of pious memory and very dear to us in the grace of Christ), who had consulted you on this question, — I did not add it to the others for two reasons, first—because, in examining this opinion, we discuss not the incarnation of the soul, but its nature; secondly, because this is the view held by those against whom I was arguing, and the main design of my argument was to prove that the blameless and inviolable nature of the Creator has nothing to do with the faults and blemishes of the creature, while they, on their part, maintained that the substance of the good God itself is, in so far as it is led captive, corrupted and oppressed and brought under a necessity of sinning by the substance of evil, to which they ascribe a proper dominion and principalities. Leaving, therefore, out of the question this heretical error, I desire to know which of the other four opinions we ought to choose. For whichever of them may justly claim our preference, far be it from us to assail this article of faith, about which we have no uncertainty, that every soul, even the soul of an infant, requires to be delivered from the binding guilt of sin, and that there is no deliverance except through Jesus Christ and Him crucified.
Source: Letters (New Advent)