There's no mistaking that Norman Rush is a writer of serious fiction. He embodies the image: in person, he's earnest, focused and controlled. Words like "obsessed" and "driven" pervade his conversation. Tall, meticulously groomed, with a neat cap of white hair, a tamed mustache and a trim beard, he exudes the gravitas, and in a way the charisma, of a dedicated creative artist.

An interview with Rush is like an immersion course in literary fervor. His latest novel, Mortals, just out from Knopf, is set in Botswana, as were his two previous works, the short story collection Whites and the National Book Award winner Mating. Mortals is a long, ambitious narrative about human passion and frailty set against a canvas of political and social upheaval. On one level, it's a romantic farce and domestic tragicomedy. In a larger context, it's a political thriller that's an indictment of Western interference in African culture. It's permeated with the themes of trust and betrayal, both sexually and politically, and filled with ironies and paradoxes.

Descriptions of this novel must include the phrase "long awaited." In 1989, Rush told Contemporary Authors that he was working on "a final Africa book, tentatively titled Kerekang the Incendiary, which is about Americans and other whites in Africa under the aspect of violence." He expected publication in 1992. Instead, the writing dragged on. "It took me a terribly long time to get this done," he says. "I wanted to exhaust the themes that had been obsessing me in my work." Struggling with a plethora of material, he says he wrote two novels with "bad" endings, both of which were overfilled with political background. "If you think 712 pages is long..." he says, arching his expressive eyebrows.

Fully thought out well before Rush began to write, Mortals advances on several levels. In contrast to Mating, which was a novel of courtship, this is a novel of marriage, "an extended meditation on a particular marriage and the fate of a besotted hero. In Mating, the theme of a utopian community was arranged over the cliché of boy-meets-girl. Here, the main themes are laid on the structure of a romantic triangle." Rush says he wanted to examine the question and nature of adultery as seen from the standpoint of a man. The speaking consciousness is that of the male protagonist, Ray Finch, a CIA contract agent, who is afraid that his need to keep his life secret is alienating his beloved wife's affections, to the point that she becomes romantically involved with a fiery African-American, Dr. Morel, who insists that Christianity and Western values have wrecked Africa.

There's a second, intersecting triangle, about the CIA's interference in African politics, with violence the ultimate result. "In Mating, the focus was on whites making a benign impact, an attempt at a benevolent interaction with African culture. The two books together constitute a kind of exercise that runs the gamut of the Western presence in Africa," Rush says.

"Wrestling with all of this took time," he continues, with grim understatement. "I was obsessed [that word again] with not falling below the standard I set myself in Mating. All of this sturm und drang was in my house, in my soul." His editor at Knopf, Ann Close, was "a paragon of divine patience," he says. One only has to read the dedication of any of his books to understand the essential support of his wife, Elsa, whom he credits with "extraordinary forbearance, creative impatience and unfailing love."

While it's obvious from his concern with illuminating moral issues that Rush was destined to become a writer, one wonders what his career would have been like without the fateful five years he and Elsa spent in Botswana, as codirectors of the Peace Corps operation there. From 1978 to 1983, they supervised the volunteers there. As State Department employees, they were members of what's called the "country team." As one can learn from Rush's books, Botswana is a very unusual society for Africa: it's a democracy; there's virtually no violence or major graft. The national culture places great value on ceremonial manners. The exacting etiquette includes a ritual of politeness exemplified by a respectful greeting before even the slightest conversation can occur.

But Botswana was of great interest to the CIA because of its proximity to South Africa, Rush explains. The CIA's presence in Africa was "all about vanquishing communism. Yet the gigantic struggle is essentially over when the book begins. I thought, this astonishing event has not found an echo in contemporary serious writing. There have been half-hearted exploitations of it in certain genre novels, but it hasn't been treated in a serious or heavy way." The fall of communism was "a double blow in Africa" because many of the liberation movements were heavily influenced by the Russian model, and they were emerging at the same time that socialism/communism was collapsing elsewhere.

In Mortals, the head CIA agent in Botswana, named Boyle, is a fussy despot obsessed with secrecy. He's almost a cartoon figure in his determination not to reveal his true role. Yet Rush says that his portrait of Boyle is not really a caricature. In reality, he found, the CIA's elaborate attempt at secrecy, everybody operating under token jobs, was ludicrous. "There was very little going on in the CIA that people had not picked up on," Rush says. His fictional CIA is misinformed and extremely damaging. Boyle focuses his hostile scrutiny on an idealistic revolutionary named Kerekang and sends Ray into the Kalahari desert to track the man and destroy his movement. Reluctantly leaving Iris, Ray begins his dangerous mission, but he disobeys Boyle's orders and in doing so finds his moral center. Ironically, for the first time in his career, he behaves according to the standards he's been searching for. It's his finest moment, and also his belated coming-of-age, but it marks the destruction of his marriage and his expulsion from his home in the section of the city of Gaborone named Paradise.

The reference to Paradise is not accidental. Ray's cover job is head of the English department in a private school in Gaborone. He's a specialist in Milton, whose poetry he relies on for emotional sustenance. Indeed, the canon of Western literature is a prominent presence in Mortals. Ray is accustomed to finding aphorisms and analogies in literature. Iris is "cursed with good literary taste." Kerekang quotes Tennyson; another character, Ray's brother, whose book manuscript Ray lugs throughout his ordeal, invokes Oscar Wilde; during his dangerous adventure in the desert, Ray finds himself recalling lines of Kipling and Yeats. Ray is also resentful that his longtime writing project, providing background biographical information that the agency calls Profiles but he calls Lives ("something of clear literary merit"), has been nixed by Boyle.

Clearly, the subtheme of Mortals is an argument or recurrent consideration of the question: What is literature for? More specifically, Rush says, "What's it for in normal domestic events and conjunctures of life, and what's it for in time of crisis? There is a question about English literature as a dilute secular religion containing injunctions, conclusions and theories of consequence. Also, it's about the humanities generally, and how they are important to people under threat."

Rush, whose cool blue eyes have fixed his questioner throughout our conversation, is especially intense when he talks about the moral and civic responsibilities of literature. The expansive action of his hands, reaching wide to illustrate the capaciousness of his vision, betrays his intensity to be understood.

Much as Western literature inspires and comforts his characters, Rush is unsparing in condemning the Western practice of assuming that our values can be imposed on African culture. The narrative makes clear that Westerners' ideas are filtered through a sensibility alien to Africa. There's a cultural dissonance, a disjunction between what a Westerner understands as normal and the different paradigms existing there. Although Americans try hard to respect the native culture, Rush believes, they understand less about the nature and the depth of their contribution. To Westerners, for example, sunglasses are one of the gifts they have contributed to the African climate. Yet in hiding the wearer's eyes, sunglasses make it impossible to show appropriate respect and deference, the Batswana believe. "There's a kind of berserk purity or innocence about what we do," Rush says. Yet he sees both sides. In Mortals, Dr. Morel, who preaches the villainy of Western influence, is balanced by Kerekang, who is aware of the beneficial effects of Christian doctrine. "It represents a kind of honest division of mind," Rush says.

Constructing and balancing these themes in a complex plot, is, of course, a daunting chore. Rush habitually makes his job somewhat easier by constructing elaborate dossiers on all his characters, giving them detailed histories and predilections. "Once I build the characters, the boxes fill in."

An unintentional irony, and a factor that delayed the novel, was Rush's original conception of his protagonist. "I began the novel with a more distant and in fact hostile attitude toward Ray. I was writing from a traditional critical standpoint, the typical feelings about somebody in the CIA. As I wrote the book, I began to like the character so much better; I developed sympathy and identification with him." Once he acknowledged his change of heart, Rush had to "do a certain amount of backtracking" in the manuscript.

In explaining the mellowing of his opinion, Rush himself relaxes, becomes less tightly coiled. He smiles broadly when PW mentions the appearance in Mortals of Paul Ojang, the ill-used protagonist of "Thieving," a story in Whites. Forced into thievery in his youth by what he believes is the will of God, Ojang is still at the trade when he runs off with money in Mortals. Rush throws back his head with a hearty laugh when PW admits satisfaction that Ojang is at last achieving success.

He's equally benign about what will be the inevitable reference to other works set in Botswana, the Precious Ramotswe mysteries of Alexander McCall Smith. "They give a good representation of the kind of fundamental civility to be found in Botswana. I try to show that in my characters, too." But the difference between the sweet-tempered tone of the mysteries and Rush's work can be apprehended immediately from a glimpse of the jackets of Rush's books. All of them are clothed in unmistakable images from Hieronymus Bosch's The Garden of Earthly Delights. It's not a random decision; Rush was determined from the beginning to use Bosch as cover art. "Is this not a ravishing cover?" he asks rhetorically, holding up a copy of Mortals. "The images are absolutely perfect for what I've tried to do." They speak to both the comedy and the strangeness and the tragedy of the events in his books. He credits Knopf art director Carol Carson with the ability to understand and implement his vision.

Rush says he's now "finished with Africa. For now I can honestly say I've ended my trajectory." He's hard at work on a new book, which will be short, he insists. It's a social comedy set in America, about a man who has an obsession with the sources of evil. Tentatively titled Subtle Bodies, it takes place in the seven days before the U.S. invaded Iraq. Politics is never far off in Rush's view of the world, and given the satirical jabs Rush takes at American culture in Mortals, his new book undoubtedly will have a deep bite.

Rush has some fears about the reception of Mortals. "I hope the length of this novel will not be discouraging to readers. There's a calculated risk in letting the book be that length. But I wanted the themes to be fully explored in this particular aesthetic configuration. It's the result of genuine intellectual searching on my part to add things up, to embody them in the discussions between the characters and make it fit into the circumstances of contemporary Africa. It's an attempt to extract the fullest statement of those themes that's absolutely compelling to me. That's what was driving me."

One hopes that Rush will remain obsessed and driven. Those qualities produce important books.