One of the really amazing things about this novel is how little we really know about the characters. Think about it—even when the narrator gets inside the brain of Myshkin, who is clearly the central character (hello, book title!) all we usually see is that he is puzzled or confused or can't think straight or just needs to calm himself down. Really, the primary way that we get any kind of info on whom we are dealing with is through what they do.
Hmm, no, actually, not so much what they do, as what they do when faced with a choice. It's the ultimate "show, don't tell." Characters are constantly presented with options: should Lebedev just suck it up and tell General Ivolgin that the missing wallet turned up? He could, but then he'd be a totally different guy from the one who carries on a crazily elaborate, multiple-day ruse of pretending he doesn't see it. What kind of a man would do that? Well, the kind who would also try to set up a complicated scheme to get Myshkin committed.
And the most telling choices all revolve around the marriage question. For example, we know all we need to know about Ganya from the fact that he refuses to choose between Aglaya and Nastasya, trying really hard to keep both irons in the fire even though neither of them is all that secure. And even though Myshkin also goes back and forth between the same two women, his choice (and thus character) is clearly completely different since it doesn't revolve around money but instead about whether it's better to love personally or impersonally.
Can you think of other characters who are faced with a choice? What does what they choose to do say about them?
So, no, we are totally not contradicting ourselves here, even though we did just full on say that the novel isn't too keen on characters' thoughts. Because, that part is still true—we definitely don't get any running internal monologues or psychological analysis from the narrator. But what we do get a lot of is just what the characters are obsessed with, philosophically speaking. And the way we get to see it is through the long spoken monologues where they try to lay out all of their ideas.
What's interesting, though, is that this characterization tool isn't really one that works on an character-by-character level, but instead lets us divide up everyone into categories. For instance, one core group is characters-fixated-on-death. (There's a name for a band.)
In that group, on the one side we have the storytellers: Myshkin and his execution stories, Ippolit and his confession, Rogozhin and the Holbein painting (check out the "Symbols" section to read about it). And on the other are those that have a death wish: Ippolit and his near-suicide, Nastasya and her lamb-to-the-slaughter ending. What does it say about him that Ippolit is actually in both of these camps?
Group number two is people-who-obsess-about wealth-and-power: Ganya constantly being tempted by tainted money (the bribe for marrying Nastasya, the 100 grand in the fire), Ptitsyn's self-satisfied calculations about his future, Nastasya's rejection of the all the riches Totsky tries to ply her with. How do their attitudes toward money draw distinctions between these characters' personalities?
Are there other groups of thinkers that you can separate out through a pervasive theme?
The Idiot doesn't spend too much time on appearance. This isn't your dermatological Dickens, carefully pointing out each mole on a character's face to mine some significance. Nor is this your clinical Chekov, looking each character over with doctorly disinterest. No, this is Dostoevsky, who always just sounds way too out of breath and lost in thought to have paid much attention to what anyone looks like.
This is exactly why, when some character's appearance does register, it's all the more telling. In this case, the two characters whose features are so striking that they totally stand out from everyone else around are—drum roll please—Nastasya and Rogozhin. Nastasya has a face that is both beautiful and full of all kinds of suffering. Everyone who sees her can't help but think about the weird combo of pleasure and pain that she's got going on.
Rogozhin's most striking features are his creepy eyes. They are so powerful that Myshkin and Nastasya can always pick him out of a crowd, even when he's trying to hide. Hmmm. In a way, we could say that because these two are so different from everyone else (since they are so facially gifted), they are clearly shown to belong together from the start. Did you notice anyone else's appearance get more than a brief once-over?