Like many students, Augustine wondered what benefit his studies had been. He had mastered Aristotle’s Ten Categories but this knowledge did not bring him any closer to the truth he desired. Augustine thought that most who read and taught on the Ten Categories did so out of vanity and not out of a sincere desire to discover the truth. He eventually came to the opinion that the mastery of Aristotle’s Ten Categories actually led him further from the truth because through them he came to believe that everything that existed could somehow “be comprehended under the ten categories” and that there was no essential difference between himself and god.
So what good did this do me? I thought that you, Lord God and Truth, were like a luminous body of immense size and myself a bit of that body. What extraordinary perversity! (IV.xvi.31)
Augustine did not see any alternative to this pantheistic view of god for he was as yet unacquainted with the God worshiped by the Christians. Although his mother was a Christian, he had come under the influence of Manichean teachers who taught him that the God revealed in the Old Testament had a human form and that the Old Testament contained laws belonging to a barbaric age.
…and it was as if some sharp intelligence were persuading me to consent to the stupid deceivers [Manichean teachers] when they asked me: ‘Where does evil come from? and is God confined within a corporeal form? has he hair and nails? and can those be considered righteous who had several wives at the same time and killed people and offered animals in sacrifice? In my ignorance I was disturbed by these questions…
What changed Augustine’s mind? Augustine said that it came through the teaching of Ambrose of Milan who opened the Scripture to him. He learned from Ambrose that the God revealed in the Bible was not anything like what his Manichean teachers had taught him. In particular, Augustine was struck by the truth that God exists apart from nature and is not to be found in one of Aristotle’s ten categories!
I was unaware of the existence of another reality, that which truly is… (III.vii.12)