An interesting dialectic animates The Last Samurai, propelling its characters through the plot and you, the reader, through its prose.
On one hand you have impulsiveness—mad, bad, dangerous to know frivolity of action and desire.
On the other, obstinacy, stubbornness, persistence. Pertinacity.
Both sides are forms or modes of obsessive reading, and as obsession and reading are both categories which naturally overwhelm, it is sometimes difficult to tell whether DeWitt values impulsiveness and obstinacy differently or even sees much difference between them. The Last Samurai, after all, is less about modes of obsession than about the way obsessions—any and all—can be diverted.
But the modes which obsession can occupy is a fascinating question, especially within the context of the novel, which is to say, especially within the context of reading.
Both Sibylla, the mother, and Ludo, the son—as well as Sibylla's mother and father and the whole host of surrogate fathers Ludo interviews—possess both ends of the dialectic—DeWitt does not set them as representing opposite forces, or really oppose anyone to them. DeWitt loops impulsiveness and obstinacy into one another in a sort of Gordian knot which each principal character toys with fitfully, often finding this combination as much of a weight as a puzzle or challenge.
Ludo throws himself about from one language to another, learning them almost frivolously, but as we see and likely know from experience, it takes a great deal of perseverance to undertake even one such project, much less the twenty or so Ludo claims. Sib herself is much the same way, although with perhaps more impulsiveness in terms of her leisure reading than Ludo and more obstinacy in terms of her "work"—transcribing back issues of dusty British mags with titles like "Carp World" or "The Modern Knitter."
It seems evident that for DeWitt, or at least for her genius characters, initial impulsiveness is the fundamental condition for developing the obstinacy required to complete the sole task of genius—to become more of a genius. Sibylla even refers to this relation directly—she calls Ludo a "miracle of obstinacy."
The miraculous and the obstinate are not usually conjoined, even if they are not exactly antithetical. But a methodical impetuosity does seem a bit paradoxical, although that would be a very good way of describing Ludo's regimen of self-education.
A wrinkle is added, however, with the central trope of the novel—Sibylla's compulsive re-watchings of Kurosawa's The Seven Samurai. This repetition is neither impulsiveness—the frequency with which Sibylla sees the film makes it more of a reflex than an impulse—nor obstinacy—it becomes not a project requiring gritty determination, but an escape offering relief. Telling is the fact that although Sibylla is always watching the film she never learns the lines in Japanese, even though she knows quite a bit of the language. This element of repetition may be the true antithesis to the miracle of obstinacy represented by Ludo, although it must be said that it is only one part of Sibylla's character and that largely she too is a miracle of obstinacy.
These three elements, though, present the three main forms of obsessive reading—repetition, impulsiveness, and obstinacy. As passionate readers, we tend to assume one or more of these forms—the compulsive re-reader who will turn again and again to the same page or the same chapter, seeking a duplication of past pleasures. Or we grab at random books off an arbitrary shelf, selecting based on spine design, if not something even more trivial. Breadth and eclecticism rule our rationale; we can be interested in anything, so long as it is written to engage. Or we read assiduously a list of ready-made orders and rolls, canons and their bastard Southern cousins, the top ten lists. Many of us rotate through these modes; as few of us read with a steady perseverance as read with a truly frivolous eclecticism.
I am unsure what my larger point is here (that readers differ from their past and future selves as much as they do from other people? that's inane), but I found the brief taxonomy I laid out here to be a greatly enriching aspect of DeWitt's work. I have a great deal of trouble being disciplined enough (or frivolous enough) to read what I feel I need to; it sometimes bothers me a lot, and DeWitt's novel lifted that from me for awhile.