William Blake saw a world in a grain of sand, but it took Karl Ove Knausgård to uncover for us the vast galaxies of meaning in cornflakes and pickled herring. Behind the maddeningly meticulous transcription of everyday phenomena in his improbably popular 3,600-page novel series My Struggle lies, to my mind, a latent faith – the faith of a mystic – that everything, however seemingly mundane, has a secret waiting to be unveiled. That mystical strain is much more explicit in the novels published either side of My Struggle. In A Time to Every Purpose under Heaven (2008), Knausgård had written about a man obsessed with meeting angels, while 2020’s The Morning Star riffs on the devil. In that novel, which inaugurated a new series, supernatural occurrences spook the populace after an unidentified celestial body appears over Norway, the “Morning Star” of the title, known as “Lucifer” in Latin. Should there be any doubt about its diabolical inspiration, the book is 666 pages long and the accompanying bibliography, published online, includes numerous titles on satanism. With The Wolves of Eternity, the series continues in this vein. It’s not a conventional sequel; plot-wise, the only link is the late emergence of the “Morning Star”. This establishes that the characters in both novels, while different, do live in the same fictional universe. Moreover, it points the reader to the cosmological intent of the novels, their questioning of humanity’s place in the universe and the nature of life on Earth. Like its predecessor, The Wolves of Eternity comprises an assortment of first-person narratives. But it’s less sprawling, more balanced; revolving around two poles. On one hand is Syvert, whom we meet in 1986 as a teenager discharged from Norwegian military service. On the other is Alevtina, a biology professor moving in more intellectual circles in Putin’s Russia three decades later. Syvert can only find work as an undertaker. His widowed mother is fatally ill. Life, as Knausgård readers know well, can be grim in rural Norway. One day he finds a stash of letters to his late father from a longstanding lover in the Soviet Union. The shock takes years to process. Eventually, the adult Syvert writes to the address the letters came from. It soon transpires that he has a long-lost half-sister, Alevtina. In the 19th century, Russian literature fixated on the theme of duality; doppelgangers abounded. There’s something of that in Alevtina and Syvert: of similar age, sharing genetic material but distinguished from each other by a lifetime spent in opposing socioeconomic systems. If chance had determined otherwise, the undertaker, whose business is death, might have been the biologist, studying the beginnings of life. When at last they meet, Alevtina and Syvert are struck by the miracle that the dead survive in their children; Syvert finds in Alevtina a manifestation of his departed father, and in Syvert Alevtina can glimpse the father she never knew. Despite this occasional poignancy, The Wolves of Eternity is a cerebral book with a peculiarly Russian heaviness. The debt to Dostoevsky is self-consciously hinted at. The letters are translated by a pastor who had learned Russian in order to read Dostoevsky. Instead of a fee, he insists Syvert read Crime and Punishment. As in that novel, long existential debates proliferate. “Billions of years ago there was nothing, and out of that nothing the entire universe came into being in an enormous explosion?” the pastor asks Syvert. “Out of nothing?” This incredulity towards scientific materialism is foundational to the book. In similar dialogues with Alevtina, Darwinism is disputed. She professes biological reductionism to unconvinced students, but it masks secret doubts. Earlier in her career Alevtina had ascertained that trees were sentient, conscious, communicating beings; freaked out by their “secret languages, codes, strange forms of cognition”, she buried the project. Heaviest of all is the extract from a book by Alevtina’s friend Vasya, “The Wolves of Eternity”, a treatise on the 19th-century Russian Orthodox visionary Nikolai Fyodorov. He believed it was physically possible to bring the dead back to life (something that does happen in The Morning Star). Fyodorov’s ideas feel strangely contemporary – reminiscent of our transhumanist moment, with techno-futurists in the place of loopy theologians. “It’s no longer just the Church that talks about eternal life,” says Vasya. “Science does too.” Much of the writing is vintage Knausgård – the style remains flat and free of artifice – but the vision is somewhat different. Way back in My Struggle, Book 1, Knausgård bewailed: A world that after three hundred years of natural science is left without mysteries. Everything is explained, everything is understood, everything lies within humanity’s horizons of comprehension. In The Wolves of Eternity, Knausgård revisits these horizons, only now he speaks of their limits, of the inadequacy of science: The nature of the mind was something that lay beyond our horizon of understanding. The nature of the universe and the atoms: beyond. Time: beyond. Death: beyond. Mystery has returned. Such metaphysical speculation can be tedious; we are so unused to it nowadays. Many will decline to endure. At 789 pages, The Wolves of Eternity is big, like the questions it entertains. This is a novel fascinated with undoing death, but perhaps its most interesting resurrection is that of a dormant form: the novel of ideas. Knausgård, master of fiction as an inquiry into the self, now revives fiction as an inquiry into the cosmos, re-enchanting the latter with those beguiling secrets science had stolen from it. The Wolves of Eternity by Karl Ove Knausgård, translated by Martin Aitken, is published by Harvill Secker (£25). To support the Guardian and the Observer buy a copy at guardianbookshop.com. Delivery charges may apply.