In Dostoyevsky's The Idiot, Prince Myshkin, the penniless last scion of an ancient noble family, arrives in St. Petersburg by train from Switzerland, where he was treated for a mental illness that remains somewhat mysterious. Prince Myshkin is meant to be a Don Quixote figure, as Dostoyevsky openly hints a few times during the book. The novel attempts to be a devastating indictment of Russian high society at that time by showing that a perfectly good man could not survive in it and would be driven to madness; but the attempt is hardly successful. In the brilliant Part I, which is self-contained enough that it could almost be a short story on its own, Dostoyevsky seems to be on his way to success. Alongside the shiningly innocent Myshkin in Part I is the "lost woman," Nastasya Filippovna, an orphan from the provinces, raised for a time with the family of an aristocrat's steward until the aristocrat seduces her, after which she comes to St. Petersburg and blackmails him into letting her live in luxury... a striking, desperate character, to whom Myshkin is immediately drawn out of compassion. But after Part I, Nastasya Filippovna's tormenting of Myshkin and another suitor makes it very hard to regard her sympathetically. And Myshkin, too, becomes less impressive: his ongoing compassion for Nastasya Filippovna, for example, becomes a grotesque indulgence.
One of the best features of the later Parts of the book is that it's incongruously comic. The extravagant sycophant Lebedyev, and General Ivolgin, an old man with a habit of romancing (lying) about his own past, are hilarious characters, and the Epanchins-- the respectable family who are at the heart of the society that Myshkin falls in with-- and even Myshkin are sometimes quite funny. The most original character is Ippolit, a sickly young man who is dying of consumption and manages to take advantage of this fact to be by turns charming and repugnant, but almost always unexpected. Dostoyevsky also writes some amusing satirical commentary on contemporary Russia and nature, in the author's voice rather than through the characters. In a book meant to echo Don Quixote, perhaps humor is appropriate? But then why does the book have to end with a gruesome and gratuitous, if not indeed implausible, murder? If you know, or anticipate, that it will end like that, you can't wholeheartedly enjoy the humor; if you don't, and you start to think you're reading a hilarious satire, the ending will feel like a nasty shock and a sort of betrayal.
All in all, The Idiot is not a particularly successful book, though there are enjoyable parts and many signs of talent in it. Certainly it's not the equal of Crime and Punishment or The Brothers Karamazov. Dostoyevsky doesn't succeed in executing his own concept for the book convincingly, and while the book sometimes seems to be evolving into something else, Dostoyevsky ensures that this evolution remains abortive by attempting to force it back to his original theme.