In his grandly melodramatic poem “The Ship of Death,” D.H. Lawrence urges the reader to prepare for the end: “Have you built your ship of death, O have you?/O build your ship of death, for you will need it.” Almost everyone manages to build some kind of ship for the journey into the unknown—constructing it out of faith, or hope, or the embrace of oblivion. It is the rare person, and the rare writer, who simply refuses to build a ship of death—who stands on the shore of life, naked and undefended, until the waters rise and he is consumed. There is something disturbing about such a figure, for he seems to mock all our preparations as vain, even cowardly. But at the same time, there is something pitiable about his improvidence. To be left at the end of a life with no resources for meeting death looks like an admission that one has learned nothing.

Nathan Zuckerman, the most maddening and cunning of Philip Roth’s alter egos, has always been defined by his refusal to learn. To mature, to grow up, to grow wise—to Zuckerman these aren’t just impossibilities, they are delusions, the lullabies we sing ourselves to drown out the voice of desire, which is the one real voice. All of Mr. Roth’s incarnations share this trait to some degree—whether he is called Zuckerman or Portnoy or Kepesh or Sabbath, the Philip Roth hero is defined by being ineducable.

But the Zuckerman novels present the antinomian challenge of Mr. Roth’s fiction most clearly, because Zuckerman, like Mr. Roth, is a novelist, and the idea of an ineducable novelist is especially goading. Isn’t a novelist supposed to see more of life than the rest of us, and to master it through his art? To be at once a great writer, like Philip Roth, and a roaring id, like Nathan Zuckerman, is therefore more than a paradox: it is an existential menace. If the artist who sees most learns least, then his art cannot console. Zuckerman offers an anti-catharsis: we leave our encounters with him angrier and more confused than before.

“Exit Ghost” (Hougton Mifflin, 304 pages, $26) Roth’s latest book, is the ninth Zuckerman novel, by the publisher’s reckoning. Really it is the sixth, because in Mr. Roth’s novels of the 1990s — “American Pastoral,” “I Married a Communist,” and “The Human Stain” —Zuckerman functioned only as a stenographer of other people’s stories. The new novel is the first time since “The Counterlife,” Mr. Roth’s 1986 masterpiece, that Zuckerman takes center stage, in all his comic awfulness.

“The Counterlife” recounts a variety of contrapuntal futures set in motion by the dilemma faced by Zuckerman’s younger bother, Henry, in deciding whether to risk a dangerous heart operation to restore his potency. In one of the novel’s linked stories, Henry undergoes the operation and dies; in another, he lives and moves to Israel; in yet another, it is Zuckerman himself who has the heart condition. In every case, however, the choice Mr. Roth poses is stark: if you put sex at the center of life, is life without sex worth living?

Now, 21 years later, Nathan Zuckerman is faced with another version of the same dilemma. But the sexual existentialism of “The Counterlife,” which made the choice between sex and death a portentous one, is pathetically chastened in “Exit Ghost.” For the past decade, Zuckerman tells us, he has been living in strict seclusion in the Berkshires. If this retreat sounds monastic — especially for a character who, in “The Anatomy Lesson,” was seen juggling four mistresses — that is no accident. His withdrawal from the world coincided with the removal of his prostate, which left him not just impotent but incontinent. The heroic choice that Zuckerman faced in “The Counterlife,” in other words, has been made for him before “Exit Ghost” even begins. In this sense, the whole book is a postlude, an examination of what happens to a man of raging appetites when he chooses life and humiliation over potency and death.

Zuckerman, we learn, has spent the last decade doing absolutely nothing but writing — he doesn’t read the newspaper, see friends, visit New York, or even accept the kittens a kindly neighbor tries to give him. This utter isolation, too, is a kind of heroism, as he acknowledges: “I stayed away because over the years I conquered a way of life that I (and not just I) would have thought impossible, and there’s pride in that.” In other words, as longtime readers of Mr. Roth will recognize, Zuckerman has managed to become another E.I. Lonoff, the hermit-like writer whom he visited in the very first Zuckerman novel, “The Ghost Writer.”

In that book, published in 1979, Lonoff’s fierce renunciation, his complete dedication to the art of fiction, served Zuckerman as an ideal and a reproach. Lonoff, who says “I long ago gave up illusions about myself and experience,” represents a kind of artist that Zuckerman knows he can never be. When Zuckerman, the apprentice writer, masturbates in Lonoff’s study, he is crudely asserting his own lifeforce against the deathly discipline of the older master: “Virtuous reader, if you think that after intercourse all animals are sad, try masturbating on the daybed in E.I. Lonoff’s study and see how you feel when it’s over.”

Now, with his id surgically removed, Zuckerman too has become a living superego, forced to sublimate the urges he once messily acted on. Even his house in the Berkshires, he tells us, is just a few minutes away from Lonoff’s. Yet it is typical of Mr. Roth that he should not try to dramatize Zuckerman during what might be called his Lonoff period. Instead, he resumes Zuckerman’s story only in the fall of 2004, when he suddenly tries to reimmerse himself in the waters of life. As the new novel opens, Zuckerman is at Mount Sinai Hospital, consulting with a urologist who encourages him to believe that his incontinence can be alleviated. The required operation, which involves injecting collagen into the neck of the bladder, is neither very reliable nor very effective: At best, it means “reducing ‘severe incontinence’ to ‘moderate incontinence,” Zuckerman says. His impotence cannot be cured at all.

But even this small chance of regaining a purely symbolic manhood is enough to launch Zuckerman into one of his old manic escapades. Looking through the New York Review of Books for the first time in years, he comes across an ad offering a house swap, and decides to trade his house in the country for an apartment on the Upper West Side. When he goes to see the apartment, he finds that it is owned by a pair of married writers — Jamie, a beautiful heiress from Texas, and her adoring husband, Billy. Instantly, Zuckerman starts to lust after Jamie, allowing Mr. Roth to engage in the kind of cool, prurient appraisal that has been a feature of his writing for 50 years: “Her sensual presence was strong — perhaps she kept herself on the thin side so it wouldn’t be stronger. Or maybe so it would, since her breasts weren’t those of an undernourished woman.”

All the instincts Zuckerman thought were dead come clamoring back to life. In keeping with Mr. Roth’s eternal view of human nature, renunciation, like repression, is proved to be a lie: as soon as temptation appears, the appetites take the reins. Lust is Zuckerman’s greatest temptation, but there are others—the passion of politics (the book takes place during the week of the 2004 election), and also of literary politics. For while Zuckerman fantasizes about Jamie, he is simultaneously drawn into an intrigue with Jamie’s college friend Richard Kliman, who declares that he is going to write a biography of E.I. Lonoff, and wants Zuckerman’s help.

It is not just Zuckerman’s distaste for this prospect, and for Kliman’s pet theory about the wound behind Lonoff’s bow, that makes Kliman such an unambiguously horrible character. After all, it is Mr. Roth, not Zuckerman, who named him Kliman (“climbing”). But Mr. Roth does at least allow the reader to see that Zuckerman’s total opposition to Kliman — “I’m going to do everything I can to sabotage you,” he shouts at the younger man—is exactly the reverse of Lonoff’s own treatment of Zuckerman, in “The Ghost Writer.” When Zuckerman came to Lonoff seeking his blessing, the older writer granted it; now that Kliman wants to claim Lonoff’s legacy for himself, Zuckerman adamantly refuses. And his desire to preserve Lonoff’s cherished privacy is clearly not the whole reason. Zuckerman tortures himself with fantasies that Kliman is Jamie’s lover: He imagines their sadistic lovemaking in bitter detail (“Let’s play the strange games. Say the devilish things”).

What Zuckerman really has against Kliman is simply his youth: “forty-three years younger than me, a hulking, muscular figure wearing just his running attire.” For Zuckerman, eternally unwise, is of course completely unable to become what Lonoff was—a good father. The good father recognizes the inevitability of his decline and supersession, and frees the son from guilt over taking his place. Zuckerman, who has no children, cannot attain to this kind of wisdom, any more than to any other kind. He will not relinquish his claims to Lonoff, or to Jamie. He can only be the bad father out of Freud, the one whom the son must kill in order to get him out of the way.

In this final episode of Zuckerman’s life, then, Mr. Roth allows his creation only one dignity — the dignity of consistency, which is the one virtue he has always cherished. Zuckerman resists every attempt to inveigle him away from his self — in the name of art, or ethics, or Jewish solidarity. He clings to his own will as the one certainty in the universe. Even now that his body betrays him, Zuckerman’s will remains constant in defeat as it was in the days of victory.

That is why, at novel’s end, when Zuckerman inevitably returns to his valetudinarian existence in the country, it does not feel like a dignified resignation. It is a bitter, Lear-like defeat. “The urologist could change nothing, as I could change nothing,” Mr. Roth writes. “I may have accumulated over four decades the prestige of writing book after book, but I had reached the end of my effectiveness nonetheless.” Even if the prose in “Exit Ghost” is a little wan, and the observations of contemporary life a little cranky (Mr. Roth has discovered the cell phone, and he is not pleased), this ruthless honesty makes it a vital book, and a worthy conclusion to the Zuckerman series. Mr. Roth, a Nietzschean writer who has always novelized with a hammer, is still strong enough to turn the hammer on himself.

akirsch@nysun.com