St. Augustine picks up a pen and starts jamming with himself. He gives one line of dialogue to PURE REASON and one line to himself. His quest is to understand the nature of God and the soul and especially to find out if the soul is immortal.
The voice of reason comes in pretty strong when St. Augustine first asks himself, Ok, but how will I know when I get my answer? Since I don't know the answer isn't it quite possible that I'll quit investigating early or too late and accept an untruth?
I love the subtlety of that question so much. How do we know when an answer is right? Something to think about and the question alone is worth asking.
Unfortunately, St. Augustine sort of loses that question and accepts an easy answer for it (basically "because God")
As the dialogue continues, St. Augustine basically pushes the entire thing into this rehash of Platonic ideals. "If something chaste dies, does chastity die?" and he basically works himself up to deciding that because the soul is the mind and the mind is the essence of living then basically an individual mind must live on because it is an essence.
I know so many Christians are so enamoured with the idea of St. Augustine as a great formidable mind who can "prove logically" that God exists (a similarly wrong claim often made of C.S. Lewis as well) But he's just a man doing the absolute best with what he has. We all start with our assumptions, but Augustine feels particularly burdened with them because of when and where he comes from. His Reason is almost uniformly excellent, but we all learned from that exercise in pure logic, computer science that putting Garbage In sends Garbage Out.
The fact is he is working at trying to figure out if the soul is immortal, but he has not defined soul (or rather he has used it in multiple and flexible ways) and he has already decided God exists.
But this does not have to be a point against him. This was a very complete and honest accounting of his thought process and was very interesting to read. The process itself was not actually wrong. He serves as a good model for self reflection.
If done well this technique can serve to expose holes in your knowledge and reasoning. But it cannot expose the assumptions you're working with- those are built in and this method can serve to make your own assumptions stronger.
This is some of his very early work and he apparently in the future revisited this question without leaning at all on the ideas of Plato. I'll be interested to see how it pans out.
This is worth a look for those curious about St. Augustine or historical philosophy. The sentences are long and hard and full of concepts unfamiliar to the modern reader and so is not really appropriate for casual toilet reading. And anyone on their own religious quest is probably better off skipping this one.
All the best parts of this are where he gets into these tangents with himself about, say, the nature of truth, or hypothetical questions. If I had a time travelling device, I'd love to see how he would proceed in the modern age.