At the suggestion of Jerome, Marcellinus (for whom see Letter CXXVI.) had consulted Augustine on the difficult question of the origin of the soul but had failed to get any definite opinion from this latter. Augustine now writes to Jerome confessing his inability to decide the question and asking for advice upon it. He begins by reciting -- and justifying -- his own belief that the soul is immortal and incorporeal and that its fall into sin is due not to God but to its own free choice. He then goes on to say that he is quite ready to accept creationism as a solution of the difficulty if Jerome will shew him how this theory is reconcilable with the church's condemnation of Pelagius and its assertion of the doctrine of original sin. The damnation of unbaptized infants is assumed throughout.

The date of the letter is 415 a.d. Its number in the Letters of Augustine is CLXVI.