Here’s a chunk from volume 1 where I’m talking about the apparent relationship between the respective works on the psalms of Augustine and Cassiodorus and the difference between them as authors. There’s quite a bit more to be said on this topic, though…
Cassiodorus and Augustine have a fascinating literary relationship. If you take Cassiodorus at face value, then he is doing nothing but a straightforward excerpting of Augustine’s great commentary on the Psalms. He says as much in his preface. After referring to his own perplexities on first seriously encountering the psalms, he finds all of his answers in Augustine: “So mindful of my own weakness, through the grace of God’s mercy and in brief summary I turned into shallow streams the ocean of Augustine which wells from the springs of certain psalms; so I have embraced in one volume the wide range of topics which Augustine marvellously unfolded in his fifteen decades.” (ExPs Pref., 23) In an environment where extracts from Augustine’s writing were common, it would not at all be a surprise to see Cassiodorus doing just that. Indeed, in his Institutes he expressly recommends to his readers a volume by Peter of Tripoli where the African abbot has “annotated the epistles of St. Paul with examples from the short works of the blessed Augustine. He declares the secrets of his own heart with the tongue of another and he has fitted these examples so suitably to individual passages that you might think that the whole had been accomplished rather by the effort of blessed Augustine. For it is remarkable that one author has elucidated the text from another commentator in such a way that he seems to have expressed the desires of his own heart without adding a word of his own” (Institutes, 1.8.9, 129). With such praise for this style of work, you could be forgiven for thinking that this is just what Cassiodorus has done with the Psalms—but the truth is that he has done something else quite different.
While Augustine and Cassiodorus were commenting on the same material and often saying similar things, they were two very different kinds of authors. Augustine was first and foremost an orator. He was a preacher. And, sure enough, the commentary on the psalms that we have from him is a collection of sermons on individual psalms delivered and collected over the course of decades. While reading Augustine’s commentary, it’s easy to form a mental picture of his compositional style: Augustine has walked into the pulpit holding nothing but a psalter and is expounding on it line by line before an eager crowd while a scribe in the first row is feverishly scribbling down his words into a tablet for review and transcription onto parchment later in the day. Augustine doesn’t cite authorities, he doesn’t rely on a great deal of prior research—the effect is listening to a man who has been reading and pondering the Scriptures for years standing up before you speaking off the cuff, indulging in digressions, and making the connections across the canon that occur to him on this particular day. This impression is only reinforced on the occasions where Augustine’s commentary contains two or three different sermons on the same psalm. A different day brings a different message on the same text.
Modern scholar James O’Donnell in his biography of Augustine contrasts the African preacher with Jerome: “[Augustine] did [interpretation] as a performer, not a scholar. The pulpit and its extemporaneity offered the focus for his biblical interpretation. While his contemporary Jerome was dictating volume after volume of careful biblical commentary in his study, sometimes following Greek authorities and sometimes simply translating them, Augustine the exegete shied away from that practice as time went by. He only turned his hand to writing formal Scriptural commentary a half-dozen times, and only once as a bishop, and never used an authoritative source or sources” (O’Donnell, Augustine, 133).
Cassiodorus, on the other hand, was a completely different kind of author. If Augustine was an orator, Cassiodorus was a composer. His writing shows clear, logical, organized composition both at the level of the individual psalm and across his work as a whole. His work on the psalms is not a collection of individually gathered elements. Rather, it is planned whole, carefully charted out, logically structured, with consistently executed internal logic and cross-references. Cassiodorus was not standing in a pulpit by any stretch; he was sitting at a desk with several open volumes before him—Augustine’s commentary, yes, but also reference works by Jerome, possibly the sermons of Hilary, and several wax tablets of his own notes. Some of these bore notes on the specific psalm at hand, others related to the work as a whole identifying groupings of psalms categorized by theme, topic, and theological import so that after the treatment of each psalm, its placement in the group could be identified and the other members in the group cross-referenced.