The first book is a discussion between the characters (the most famous one is Socrates) about what the best kind of society would be like if they could make it so, and the argument about justice vs. injustice. The other characters insist that it's better to be unjust than just, and they offer all sorts of arguments for injustice, though they don't really "decide" anything about this; even after Socrates has his say about why justice is better. They end at an impasse (in greek it's ἀπορɛία; aporia) where no one is "right" no one is "wrong," and the argument is just ended. One of the things that is "decided" in the first book that everyone in the argument more or less agrees with is the idea that each position in society should stick to that position. I, for the most part, agree with this though the discussion doesn't leave any room for hobbies (perhaps because in those days only the über-rich would have spare time to pursue hobbies).
Then in book two, one of the only points that I totally agree with (so far) comes out. That is, the idea that the "defender class" (i.e. the military) should be philosophers or at least think philosophically. It saddens me that the military profession has never really had this type of people in it. Don't get me wrong there are some very philosophical people in the military (many are my peers), but in general philosophy is not really a martial art.
Then book three focuses on the education of the military class, and this is where Plato and I have to part ways. Socrates speaks at great length about how this class should be educated, specifically about the censorship of the writers/poets, art, and music. Like there should be no writings of the gods that shows them doing human-like actions and having distinctly human failures. It's not really surprising the people sentenced him to death. In ancient Greece where the writings of Homer were akin to other sacred texts (the Bible, if you will, for Greek faith), and here Plato/Socrates (assuming Socrates actually taught what Plato was writing that he taught) is teaching that Homer (and others, but Homer is specifically mentioned) should be censored and NOT taught to the military class. That would be like someone in Medieval times preaching that the Bible isn't true. Basically, blasphemy, though of course it's not called that, at least not by anyone I know.
One thing isn't clear (though it doesn't matter I still disagree with him), is ALL art/poetry/music/writing to be censored? Or just that which the military class studies/experiences? Either way I disagree, the only thing I agree with is that we need to be careful about what age we expose children to certain poetry/art/music. Because, (and this is scientifically supported) children lack the ability to discern certain differences between what is real and what is fake or what is right and wrong. There is an innate sense of some right/wrong but children cannot discern real/fake. Also, they cannot see through lies or deceptions or advertisements. Up until a certain age kids don't know the diference between the TV show they're watching and the commercials. So yes, shield kids from bad influences and temptations that they cannot resist, to a point, then when a person has learned self control/Willpower, let them learn about EVERYTHING (except the darkside of the force, apparently). We want to develop a well-rounded society, so everyone should study as much as he/she can in whatever field he/she is interested in.
I'll continue more on The Republic as I listen to the audiobook, but I'm also trying to read Gödel, Escher, Bach: An Eternal Golden Braid, and it is a very heady, difficult to read book. My friend also recently sent me, The Language of God: A Scientist Presents Evidence for Belief which I'll be trying to read also while I'm away from home. I did finish Plato and a Platypus Walk into a Bar . . .: Understanding Philosophy Through Jokes, I highly recommend it as a neat/humorous introduction to philosophy.