Harry Mulisch, Holland's leading post-war writer, turns 80 on Sunday. The event is cause for nationwide celebration in Holland, where Mulisch is looked to as a national conscience of a society troubled by its history of Nazi occupation. But Mulisch says that he does not feel Dutch. "I was born in Holland, but in a way Holland was never born in me," he muses, pointing out that his Austrian father and Jewish mother were foreigners. Interviewed in his canal-side Amsterdam apartment, Mulisch looks a decade younger than his years. Wearing a pink-and-white-striped shirt and white loafers, he sports an elegant set of black-and-silver bracelets. Although supremely at ease with his importance, he surprises with flashes of boyish ebullience. "I have a theory that everybody has an absolute age which he will always have. My absolute age is 17." To flag his birthday, Mulisch's Dutch publisher commissioned six novellas from noted Dutch authors, taking Mulisch's novels as their departure points. It's an unlikely homage to a writer whose exuberantly inventive, philosophical works depart from the understated realism of most Dutch literary fiction. "Dutch writers and painters are naturalists, describing normal life. That tradition is not mine." Dutch writing is far less internationally famous than Dutch painting; even Mulisch has seen only one-third of his work translated into English. He is best known for two books: The Assault (1982), a compact, intense thriller that probes the decades-long reverberations of a political assassination in Nazi-occupied Holland; and The Discovery of Heaven (1992), a 700-page saga of divine intervention, in which Mulisch incorporates characteristically exhaustive displays of his encyclopedic learning on topics ranging from astronomy, philology and theology to architecture. Sometimes misreported as believing that the The Discovery of Heaven is his best work, Mulisch likens asking an author to choose between his books to the malicious question of William Styron's Sophie's Choice: "You may not ask a mother which of her children she loves most. I said that if there's an immoral God - and if there is a God, he would be immoral - and he says now: 'We [could either] destroy all your books but not The Discovery of Heaven, or destroy all The Discovery of Heavens but not the rest,' then I said [the former], not because I love it most, but because it's the book in which all my obsessions and themes come together." The Assault tracks 35 years in the life of Anton, an anesthesiologist whose innocent family was gunned down by the SS in reprisal for the murder of a collaborationist police officer in 1945. Only the first of five episodes is set in the war. Mulisch says that for "young people used to books about the war - The Diary of Anne Frank, for instance - the four scenes after the war gave them a contact with the war." The novel was made into a film that won the 1987 Oscar in the foreign language category. Mulisch admires the film but comments that no one has described it as an improvement on the book, which he says would be "the worst thing that could happen to me." The novel's tension reaches an apogee when Anton confronts the ex-underground member who indirectly caused his family's slaughter, liquidating the thug despite knowing that the Nazis would take revenge on local civilians. "What interested me was the difference between guilt and responsibility." MULISCH IS uniquely placed to probe the moral ambiguities imposed by history. His mother was a Jew whose entire family was exterminated, while his father was a gentile who saved his wife and son by working for the Nazis as a director of the bank where Holland's Jews were forced to deposit their assets before facing deportation. His mother was incarcerated in 1943, but Mulisch pÃ¨re's access to power meant that she was released three days later. Mulisch's unusual parentage has elsewhere led him to declare: "I didn't so much 'experience' the war; I am the Second World War." He recalls how once during the war, at the cinema, the lights came on to reveal Nazis surrounding the auditorium. All men whose identity cards showed them to have three Jewish grandparents were arrested, while those with one Jewish grandparent were sent to work in German munitions factories. But Mulisch, as a half-Jew, was free. "Two Jewish grandparents meant that you were not Jewish enough to be murdered, but you were too Jewish to be allowed to work in the German factories." His formal education was aborted in 1944 when he decided not to risk attending school any longer. Although originally set on a career in science, he turned to writing at 18, a few months after the war's end, when his first effort at penning a short story was published in a newspaper. With his father serving three years in prison for his service to fascism, Mulisch continued writing to earn enough money for two meals a day. At 23, his first novel, Archibald Strohalm, won the Rein Geerlings Prize for young writers and was published to high praise. Money was scarce in his 20s, but he found himself a patron: "A girlfriend, who had a job, thought that I was a genius - very clever girl! - and I lived on her more or less. I was very poor, but after the war everybody was poor." Over subsequent novels, Mulisch distinguished himself from his contemporaries with his intellectual game-playing and fondness for the mythical and uncanny. He feels more affinity with the lofty esthetics of Catholicism than dour Protestantism, which he says explains the Dutch resistance to fantasy and ornamentation. "Catholicism - that is statues, prayers, the pope and holy priests - is all gone in Protestantism." Some churches in Holland are still bare from when their monuments were destroyed in the 16th-century Protestant Reformation. "As a writer, I'm not in favor of destroying beautiful statues. I help make them." A SCULPTOR rather than reader of words, Mulisch hasn't read a novel for two decades. While enthusing about his close friend of five decades, fellow Dutch writer Cees Nooteboom, he admits unabashedly that he isn't familiar with his books. "People ask me often, are you still reading novels? But that's the same as if I ask a reader, are you still writing novels? If I read one page of a book, standing in a bookshop, I know whether it is okay or nothing. I don't need to read a whole book to see that." Mulisch reads only non-fiction that forms research for his novels. He gestures towards the walls of his capacious, book-lined study - here, books about theology used for The Discovery of Heaven; there, tomes about Nazism that he drew on for his 1962 essay on the trial of Adolf Eichmann, "Criminal Case 4061." His report on the trial advanced a theory of Eichmann's ordinariness similar to Hannah Arendt's study of "the banality of evil" in Eichmann in Jerusalem. "My book was first," says Mulisch, noting that Arendt cites his work approvingly. He revisits the question of evil in his most recent novel, Siegfried (2001), centering on Rudolf Herter, an aged and self-important Dutch novelist, famous for his 1,000-page opus, The Invention of Love. During a publicity jaunt, Herter is inspired to tackle Hitler when he tells an interviewer: "He's been examined from all sides... All those so-called explanations have simply made him more invisible... Perhaps fiction is the net that he can be caught in." Mulisch offers his own account of Hitler. "Nobody said he had this power, not although he was nothing, but because he was nothing. He was a kind of black hole." Siegfried imagines that Hitler had a son, and then considers his reaction to discovering that the child is 1/34 part Jewish. Mulisch wondered whether Hitler would murder him. "He made 55 million people die but none of them with his own hands, only one - he himself. I thought: 'Wasn't there something of love in this man? Was it just all hate and destroying?'" After attempting to draw the interview to a premature close, Mulisch is reengaged when asked about his collection of pipes. There are more than 80 displayed around his desk. Photographs often show Mulisch with a pipe, but he quit five years ago. "I always smoked pipes and one day I couldn't any more. It was over. I never wanted to stop smoking but I stopped." He speaks proudly of his nomination for this year's Man Booker International Award for an author's body of work, speculating about the envy of other Dutch writers. "It's a small country, but this smallness is also in the Dutchmen themselves. If there's suddenly somebody who is a really big man - let's say Spinoza - he's thrown out." But as he looks forward to a 1,000-strong birthday reception, and the array of media profiles, public literary forums and book publications welcoming him into his ninth decade, Mulisch surely knows that he's exaggerating.