THE DISCOVERY OF HEAVEN By Harry Mulisch Translated from the Dutch by Paul Vincent. Viking. 730 pp. S34.95 "I NEVER make up anything," claims a novelist-character in this prodigious novel. "I remember. I remember things that have never happened. Just like you do when you read my novel." Much the same might be said of that novelist's creator, Harry Mulisch, a Dutch writer best-known for The Assault, the gripping story of a family shattered by an assassination in front of their house during World War II. The Discovery of Heaven features angels in heaven, two close male friends who were conceived in Holland on the same charged day (that of the Reichstag fire in 1933), a preternaturally beautiful and intelligent boy, and a quest for the tablets containing the Ten Commandments (not the original tablets, which were destroyed by an angry God, but the replacements). If all this is redolent of magic realism, in Mulisch's low-key telling it's as unobtrusively vivid as a memory of events that never occurred. Mulisch is the son of a Jewish mother and a Gentile father who was arrested for collaboration with the Nazis after the war. That chilling heritage made itself felt in The Assault and does so again here, where one of the friends, astrophysicist Max Delius, hails from a similar background, with the added horror that his father betrays his wife and her parents, dooming them to Auschwitz; after the war, the father is shot by a firing squad. The other friend, dilettante and (later) politician Onno Quist, is the scion of a stuffy Calvinist family. Mulisch depicts the brilliant pair's almost scarily intense friendship in evocative images and lively talk. "But their unending stream of theories, jokes, observations, and anecdotes was not their real conversation," he writes; "that took place beneath these, without words, and it was about themselves. Sometimes it became visible in a roundabout way, like when in the past North Sea fishermen located a school of herrings from its silvery reflection against the clouds." Soon a third party complicates their bachelorhoods: Ada, a cellist. After a brief affair with Max, she marries Onno. One day, in a mad interlude, she and Max have sex again. Since she makes love with Onno just hours later, her pregnancy might be impeccable; then again, it might not -- she wonders if she isn't "pregnant by the friendship" between Max and Onno. After she is knocked into a coma in a car accident (the doing of an interfering angel), the question mark goes into abeyance. The child is born -- the extraordinary Quinten -- but Ada never wakes up. Onno and Max agree that Max will raise the boy with the help of Ada's mother, with whom he lives (and carries on an affair) in a rural castle converted into rental units. Not until Quinten is almost grown up will his two putative fathers sort out his parenthood. It's not giving much away to reveal that the angel so arranges things that Quinten gets Max's genes, benefits from Max's fatherhood up to a certain point (and, incidentally, acquires a battery of James-Bondish skills -- lock-picking, for one -- from the castle's other tenants), and then, after Max dies, goes to live with Onno as the time for Commandment-hunting draws near. Mulisch's plot is baroque and tantalizing, and the climactic episode of Quinten and Onno on the trail of the missing tablets recalls both Umberto Eco and Steven Spielberg. But it's Max and Onno's speculations -- soaring and pedestrian, cunning and crazy -- that give this novel its special flavor. Here, for instance, is Onno delivering what might be called his somatic theory of history: "Power is the power of the flesh. Power is purely physical. No one has dared face up to that . . . {Hitler's} appearance accounted for 33 percent of his effect, and all the neo-Nazis are still in love with it. And Salvador Dali once said, I love his back.' You can dismiss that as a surrealist observation by a Spanish lunatic, but it also indicates a sense of all-determining physicality. And what do you think of a remark that Heidegger once made to Jaspers, who wondered how such an uncivilized creature as Hitler could rule Germany. Heidegger's answer was, Civilization has nothing to do with it . . . just look at his wonderful hands.' Apart from that, he had a voice which went right through you, which made everything he said different than if someone else had said it. A second 33 percent of the oratorical impact of his words on the masses can be attributed to that sound. I once saw an X-ray picture of his skull in a book somewhere, and it was observed that he had exceptionally large sinuses, with extraordinary resonance. And the third 33 percent of his power was due to his incomparable body language. On the one hand his terrifying outbursts of rage at the lectern, on the other hand his perhaps even more terrifying silence: his masklike face, the precision of his pose, the tension of even the smallest movement. The way he saluted at a parade, with that slight curve of the wrist, the position of his thumb, the way he brought his hand back to his belt: all of it had bewitching power . . . What he had to say, his political aims, all those scandalous things, were no more important than the remaining 1 percent of his power. But the fact that it all happened, that it was all carried out by people who weren't basically any worse than any other people, the fact that 6 million Jews died, and 50 million others, including 8 million of those who had cheered him and paraded in front of him -- that was because of that physical 99 percent. That was the enormous extra something he had; it was his unique body that made his power absolute." LONG AS THIS excerpt is, it's only a fraction of Onno's soliloquy, which goes on to encompass such topics as DNA, freedom and the selection of a new Dalai Lama in Tibet. Later, Onno sketches for Quinten a theory of anti-Semitism that implicates the very Commandments they are searching for. "I . . . used to think that the hatred of Jews was all about Christ," Onno says, "but that isn't the case. It existed long before Christ . . . {It's based on} the fact that the God of the Jews had sanctified his people by entering into a covenant with them, which no other people can boast. Obviously an intolerable thought for many people." In the hands of most other writers, matter of this density would likely sink heavily into the page, but Mulisch invests it with a quite bearable lightness. Paul Vincent's translation seems solid, if occasionally awkward. If he could just understand that "like" is almost always a preposition, he wouldn't write solecisms such as "now he understood why Max -- like he himself, in fact -- had had four foster parents." The standard danger lurking in monster-long novels is loss of control. This is not a problem for Mulisch. If anything, The Discovery of Heaven might be wound a bit too tight, with the hand of the watchmaker-author occasionally visible, especially when those angels are on stage. But with or without them, this is one of the most entertaining and profound philosophical novels ever written. Dennis Drabelle is a Washington writer and editor.