And what did it profit me that, when scarce twenty years old, a book of Aristotle's, entitled The Ten Predicaments, fell into my hands — on whose very name I hung as on something great and divine, when my rhetoric master of Carthage, and others who were esteemed learned, referred to it with cheeks swelling with pride — I read it alone and understood it? And on my conferring with others, who said that with the assistance of very able masters — who not only explained it orally, but drew many things in the dust — they scarcely understood it, and could tell me no more about it than I had acquired in reading it by myself alone? And the book appeared to me to speak plainly enough of substances, such as man is, and of their qualities, — such as the figure of a man, of what kind it is; and his stature, how many feet high; and his relationship, whose brother he is; or where placed, or when born; or whether he stands or sits, or is shod or armed, or does or suffers anything; and whatever innumerable things might be classed under these nine categories, — of which I have given some examples — or under that chief category of substance.
Augustine, Confessions, Book IV, Chapter 16. Augustine, who knew only a smattering of Greek vocabulary, almost certainly read the book in Marius Victorinus's Latin translation. An interesting passage, both for its testimony of how difficult Aristotle's doctrine of the categories was thought to be and for Augustine's interpretation of it. Augustine seems to differ from his teachers in having a minimalist interpretation of the Categories. After Porphyry (d. 305), the Platonists seem to have largely interpreted the Categories as being about language, but earlier there were many vying interpretations, some more metaphysical and some less, so perhaps there were still controversies over the matter in Roman Carthage. Or perhaps Stoic criticisms of the doctrine were common there, creating some controversy over how they were to be answered.
Regardless, the Aristotelian doctrine of the categories plays a significant role in Augustine's intellectual life; immediately after the above passage he diagnoses his early theological difficulties as consisting in treating divine being as if it were categorical.
The categories come up elsewhere:
What, therefore, we do not find in that which is our own best, we ought not to seek in Him who is far better than that best of ours; that so we may understand God, if we are able, and as much as we are able, as good without quality, great without quantity, a creator though He lack nothing, ruling but from no position, sustaining all things without having them, in His wholeness everywhere, yet without place, eternal without time, making things that are changeable, without change of Himself, and without passion. Whoever thus thinks of God, although he cannot yet find out in all ways what He is, yet piously takes heed, as much as he is able, to think nothing of Him that He is not.
On the Trinity, Book V, Chapter 1. This passage continues the same theme as above, i.e., that one must not think of God in terms of the categories. Very notably, though, here Augustine does not list substance, and he only identifies one specific kind of relation -- a significant part of the argument of the De Trinitate is a discussion of substance-terms and relation-terms as they apply in talking about God.
