In A Nutshell
The religions of the world did not just spring into being all set and ready to go. A lot of kinks had to be worked out first—like the fact that people didn't automatically accept the idea of a God who wasn't really made of anything, but was somehow everywhere at once. And how about convincing people not to have sex? Yeah, good luck with that. Even the idea of light as good and dark as evil (ever wonder why when Obi-Wan calls it the Dark Side we immediately know it's bad news?), which is one of the oldest tropes there is, had to come from somewhere.
We're not saying that Saint Augustine's Confessions did all this work by itself, but it sure as heck made some headway in this whole building a religion business. Augustine lived way back in the 300s (CE) in North Africa, which, at that time, was part of the Roman Empire. What was going on in the 300s, you ask? Well, the emperor Constantine, who is not Keanu Reeves, basically legalized Christianity—no more getting sent to the coliseum to be crucified, hooray. Then the capital of the empire was moved from Rome to Constantinople, and, as per usual, there were a ton of barbarians doing their raping-and-pillaging thing, so you might say that Europe was in a bit of an awkward transition period.
So, the Confessions are exactly what they sound like: the confessions of this one guy. No fronting here. Was he a particularly bad guy? Not really. Augustine basically chronicles the story of his (average) life up until the point when, at the age of thirty-three, he converts to Christianity. His book is both an admission of his sins to God and an example that he hopes other people will learn from. Because, you know, converting to Christianity is exactly the kind of thing saints tend to endorse.
In this book, Augustine talks about all of his doubts about God's existence, his dabbling in other religions, his love of pride and of sex (especially sex), and how badly he just wants to know the truth. (Like, Are you there, God? It's me, Saint Augustine.)
Don't worry, Confessions is not a laundry list of every inane sin the guy ever committed. When it comes down to it, Augustine is just some dude who really, really wants to know how the universe works and how he's supposed to live his life by its rules. But the road to his conversion is pretty rocky. He runs with a weird cult for a long while, he really doesn't want to give up his mistress, and, more than anything, he wants to be known as the smartest person in town. He has a really hard time coming to terms with ideas like God's immateriality and where evil comes from in the Christian theology. Many people take these things for granted now, but Augustine believed he had to work out all of the technicalities… before he would be willing to permanently give up sex for them.
And it's a good thing that he work all this stuff out, because Augustine's writings have had a huge impact—and not just on Christianity, but on all of European philosophy. You find echoes of his thoughts on the creation of the universe, God's immutability, free will, and so on in the works of Dante, Milton, and T.S. Eliot, who are all pretty big names in our book(s).
Why Should I Care?
When you think of the "classical" texts of the ancient world, as we know you often do, you probably think of Homer, Plato, Socrates, Aristotle… and then, at some point, you start thinking of Roman dudes instead of Greek ones, and you think of Caesar, Cicero, Virgil, and so on. Basically everyone was all about Greco-Roman mythology, what with them being Greco-Roman and all. Then all of a sudden, BAM: here's Augustine developing a philosophical model based around Christianity. But is it some cold treatise on the pros and cons of converting? HECK NO. He makes it personal. He gives you a play-by-play of his sins, citations and all. Augustine is a really intelligent guy who willingly drags himself through the mud in order to teach people about God. Which is pretty nice of him, really.
Anyways, this God Squad recruitment tactic of Augustine's was pretty successful. Augustine was made a saint and declared one of the fathers of the early Christian Church. More importantly, he was hugely influential to theologians as they continued to develop Christian thought throughout the Middle Ages and the Renaissance. Sound remote and irrelevant? Well, guess what? Confession is a huge deal in today's culture, regardless of religion.
When a politician is caught in some scandal, we expect him to give a repentant speech in which he tells us all about just how wrong he was. Why? When George Washington apocryphally cuts down a cherry tree, we find it noble that he admits it even though he doesn't have any apparent reason to. Why? When the Reverend Dimmesdale doesn't confess that he fathered a child with Hester Prynne, it eats away at him until he finally does. Why? Why do we care so much about confessing sins?
We think Meryl Streep can explain it better than we can.