“A novel? No. I don’t have the endurance anymore. T o write a novel you have to be like Atlas, holding up a whole world on your shoulders and supporting it there for months and years while its affairs work themselves out.”

So says the aging writer with bad teeth and musty yellow jacket, crumbs in his beard — a more tattered version of the well-groomed man with knife-sharp features whose author photo appears on the dust jacket of “Diary of a Bad Year” (Viking, 227 pages, $24.95). The young Filipina woman he’s recently hired as his typist has just asked “Señor C.,” as she calls him, why he can’t tell a good story instead of making her transcribe a series of short essays about politics and statecraft.

To those familiar with J.M. Coetzee’s work, pleading age may seem like an excuse for continuing to do just what he’s always done. He has never really written baggy novels or created self-standing worlds. Early works — “The Vietnam Project” (1974), “Waiting for the Barbarians” (1980), “Foe” (1986) — required readers who could check off their own internal references to the Pentagon Papers, structural anthropology, Kafka, C.P. Cavafy, and Robinson Crusoe, and who also knew something of life in apartheid South Africa.

Marked by an awareness of the limits on the novelist’s authority, or any authority — primarily that of men over women and, increasingly in his recent work, of humans over other species — Mr. Coetzee’s fictions hover unsteadily between parable and a kind of literary criticism of the soul. Women characters in “Foe” and “The Master of Petersburg” (1994) offer their own countervailing perspectives on the lives and human failings of Daniel DeFoe and Dostoyevksy. “Disgrace” (1999) hints that rape and animal slaughter are points on a continuum of patriarchal vices. The novelist as Atlas has always been just one of the myths his novels aimed to break down.

True, these challenges have sometimes come in the form of traditionally “realist” novels, like “The Life and Times of Michael K.” (1983), “Disgrace,” and even the autobiographical “Youth” (2002), but these just reinforce the impression that Mr. Coetzee’s long career has been a successful effort to liberate himself: First from repressive societies, then from the necessity of having to write a particular genre. He can do “traditional” novels, even when he chooses not to. “Diary of a Bad Year” is the latest in an ongoing series of such challenges to the habitual forms we use when we think about novels and politics. Although tinged with an awareness of the author’s advancing age and diminishing of power, it’s still uncompromisingly radical in what it asks of the reader. “Diary of a Bad Year” is a novel only if you believe that literature can pull off multi-part harmonies, the kind of synchronic pluralism, that occurs, as Señor C. suggests at one point, in the choral music of Bach. In this respect, it resembles an earlier experiment, “Elizabeth Costello” (2003), a novel that can only be called a novel in the sense that Plato’s dialogues are plays. Of course Plato’s dialogues are dramatic, and literature, as much as it is something we “hear” and experience over time, resembles music. But what makes sense in theory often looks unusual in practice.

Readers will open “Diary of a Bad Year” and see first two, then three distinct voices on the same page, separated only by a thin bar-line. Here’s a novel that can be read three different ways, none of them wholly satisfying. You can’t read any one part without becoming aware that you’re ignoring the others. If you tried to read them all at once, you’d go nuts. Señor C. claims failing stamina, but Señor C.’s creator is really out to test ours and refuse us the pleasures of absorption. The top line, or melody, begins as a series of essays called “Strong Opinions” (the Nabokov allusion is probably incidental, or a kind of joke to suggest how far Mr. Coetzee will go to undermine the idea that even aging and respected writers have earned the right to spout off about the world unchallenged). These start off as a series of observations on “The Origins of the State,” “Machiavelli,” “Guantanamo Bay,” “National Shame,” “Pedophilia,” and “Animal Slaughter,” before branching off to topics such as intelligent design, probability, and number theory, and then veering back to deal with immigration politics in Australia, where the peripatetic Mr. Coetzee recently moved after years teaching at the University of Chicago.

On their own, these essays and aphorisms would constitute a most intelligent case for principled, pacifist opposition to the War on Terror and violence in general. They are also a strong defense of human freedom. The essay “On Competition” concludes,

There’s nothing ineluctable about war. If we want war we can choose war, if we want peace we can equally well choose peace … What those people who trot out the jungle analogy really mean, but don’t say because it sounds too pessimistic, too predestinarian, is homo homini lupus. We cannot collaborate because human nature — leave aside the nature of the world — is fallen, vicious, predatory. (The poor, maligned beasts! The wolf is not predatory upon other wolves: lupus lupo lupus would be a slander.)

The reaction, in the present climate, to a book of such essays — with untranslated Latin no less — probably would be either baffled outrage or indifference, or both, assuming the book even found an American publisher. Anticipating the critics — perhaps even too much so — Mr. Coetzee has provided just such a skeptical audience in the book’s “bass line.” Here is an apparently more straightforward story — or at least a plot — about an aging novelist who, while doing the laundry in the basement of his Australian high-rise, meets “a quite startling young woman. Startling because the last thing I was expecting was such an apparition; also because the tomato-red shift she wore was so startling in its brevity.” Apparently, there’s a realm of necessity after all, even for aging novelists and thinkers. But Mr. Coetzee understands the place of this kind of cynicism. Anya, the Filipina, and her boyfriend, a stockbroker, form a counterpoint to Señor C.’s essays. They read him, react to him, judge him. A third line appears, a sort of harmony in Anya’s voice. She has her own opinions, even if she’s just a girl who used to work “in the hospitality industry,” as she calls it. What happens next in this triangle is, thematically, what one has come to expect from a Coetzee novel. A machine has been set in motion that generates encounters between sets of utter opposites — man and woman, civilization and barbarism (Anya, despite her Swiss boarding school, is the latter, and the libertarian boyfriend even more so), old and young, writer and character — with the aim of undoing these very neat juxtapositions. The writer and the woman begin to relate to each other, painfully at first. In response to Anya’s complaints about the off-putting “know-it-all” tone of the essays, Señor C. begins to write more anecdotally about “the erotic life,” his dreams of death, music, compassion, boredom, the birds in the park outside the apartment complex. The tone becomes melancholic, as though Señor C. were shoring his fragments without hope of posterity.

As the authorial and authoritative presence of C. fades, Anya becomes an actual character. Her porn temptress clichés and false knowingness — “When I make my silky moves I can feel his eyes lock on to me. That is the game between him and me. I don’t mind. What else is your bottom for. Use it or lose it” — gives way to the realization that the old man “wants to be my grandfather, not my paramour.” While this isn’t quite true, Anya at least begins to see him as an object in need of care: This is not, after all, a Philip Roth novel. Señor C. knows he’s a man facing death, still susceptible to lust and beauty, but he won’t reach for any actual or metaphorical Viagra. Although C. no longer poses a sexual threat, Anya’s boyfriend still senses that he’s losing part of her to the writer and begins to plot against him. Or maybe his plotting arises out of sheer boredom. For all his emphasis on free will, Mr. Coetzee often suggests that human beings, left unchecked, are like higher carnivores who play with their prey before consuming it.

Suggestion, though, is as far as he goes. Precisely because it’s impossible to read three parts simultaneously, or hear them without succumbing to a confused babble of voices, “Diary of a Bad Year” suggests that no work of literature can do complete justice to the multiple experiences it evokes and represents; it can only gesture to them, leaving us to assemble the pieces. We don’t know for sure, for instance, that Señor C. hasn’t stolen Anya’s panties, as she claims. He is a human being, albeit a more self-conscious and dignified one than the characters he meets.

Still, Mr. Coetzee has never been sparing of his characters’ dignity. “Diary” departs from his earlier work only by inverting the terms of who suffers and who can offer consolation. Usually, it’s the voice of civilization, in the form of a (usually) male narrator, who comes to recognize that he is not alone in the world of his desires. Here, it’s the old, bachelor writer, at the mercy of strangers, who resembles the stray dogs in “Disgrace.” He cannot depend on common humanity, nor does he ever appeal to it. Anya’s emerging awareness that she can be a friend or daughter to the old man arises as a chance mutation from their relationship. One could imagine a far darker novel, a far worse year, than what unfolds. That hint of the worse things that come when we fail to listen to and be shaped by as many voices, as many “strong opinions,” as we can, echoes among the three parts of this choral novel like a last haunting and dissonant chord.

Mr. Roth is an editor at n+1.