WCXX

Stach's book succeeds brilliantly at clearing a path through the thick metaphysical fog that has hung about Kafka's work almost since his death. As everyone knows, Kafka requested that Max Brod burn his unpublished work; as everyone knows, Brod ignored the instruction, though whether Kafka really expected him to comply remains open to debate. Brod had long complained of Kafka's perfectionism in life, and, as a selfless promoter of other writers, he was determined that his friend should have his due in death. His opinion of Kafka as "the greatest poet of our time" and his barrage of stitched-together publications and commentaries managed to cast Kafka as a kind of writerly sage, inaugurating a long tradition of critical blindness to anything but the most serious, poetic and religious aspects of the work. Such interpretations were given further plausibility by the ominous metaphors of the totalitarian era in which Kafka studies came of age.

Stach sets himself to redress this balance. In addition to Doktor Kafka the doom-ridden poète maudit of Prague, he gives us Dr Jackdaw (Kavka in Czech), the charming young writer, fond of slapstick humour, who, reading the first chapter of The Trial to his friends, became so convulsed with laughter that "he could not continue reading at times" while they howled "uncontrollably". To add to Kafka the endless clerk, plagued by the job he hated, he gives us Kafka the lawyer and invaluable insurance expert, throwing his considerable organisational weight behind campaigns for hospitals for shell-shocked veterans of the trenches.

The point is not that Kafka was one and not the other. He was both. But this account seems correspondingly more fresh for the years of leaden interpretation that precede it. We encounter Kafka convalescing from tuberculosis on his sister's farm: "He picked rosehips, set up a vegetable garden, got down on all fours and dug potatoes from the ground, fed the cattle, drove the horse and cart, and even chopped wood and tried his hand — rather clumsily — at the plough." We see him with his girlfriend Julie Wohryzek: "They trudged together through short paths in the snow, launched into stories, switching back and forth between German and Czech, punctuated by laughter. And when they ran into one another, they burst into laughter before they even spoke."

Other lingering misapprehensions — particles of what James Hawes, in his satirical 2008 study Excavating Kafka, called "the K-myth" — are exploded with equal good cheer. Was Kafka unknown in his lifetime? Not at all: his publishers printed his books and begged him for more, his pieces were added to the repertoire of a famous elocutionist and reciter and he belonged to an influential band of writers, none of whom was averse to rolling a log for a friend.

But anyone tempted to discard the other point of view too quickly need only run an eye down one of the harrowing processions of nouns in the index: "selfishness; shame; suffering; suicidal thoughts; unhappiness; unspecified declines; weeping". We become grimly familiar with Kafka's health-freakery and hypochondria: his faddish eating and exercise regimes, his ghastly fantasies of penetration and dismemberment and his habit of worrying so hard over nebulous illnesses that tuberculosis eventually came, he wrote, "almost as a relief".

Stach is also good on Kafka's doomed love life, beginning with his strange epistolary courtship of the unfortunate Felice Bauer, with whom he exchanged 500 wrangling, confessional letters over five years while seemingly making every effort not to see her in person. When he eventually felt compelled to propose marriage, he did so in an 18-page document containing such inducements as "You would lose Berlin, the office you enjoy, your girlfriends, the small pleasures of life, the prospect of marrying a decent, cheerful, healthy man, of having beautiful healthy children"; and once they were married, he concluded, she would probably have to bring him his meals in a special writing cell underground.

This is a fearsome demonstration of Kafka's splinter of writerly ice in the soul, the blend of sensitivity and iron selfishness that Felice and his other intimates eventually recognised to their cost. It could manifest as masochistic self-laceration — "You are my human tribunal," he told Felice, while his later lover Milena was asked to go through his notebooks for anything "against him" — or simply as a chilly distance from the world. "Kafka once wept after reading a news report of a woman who murdered a child," Stach tells us, "but noted at the same time, 'A well-plotted story'."

Such observations are valuable because the texts themselves manifest just this kind of doubleness. By enshrining their cryptic personal symbols in a German whose purity was much remarked on in Kafka's lifetime, they became polished for public display while remaining deeply and woundingly private. "He wanted his texts to see the light of day," Stach observes, "but to remain in the dark himself." The remark helps explain Kafka's lifelong concerns over publication.

This biography is illuminating on Kafka's literary influences, including Dickens, Flaubert and Robert Walser, and particularly on his vexed relationship with Jewishness, another topic long overshadowed by history and interpretation. Brod's own ardent Zionism informed his conviction that Kafka wrote some of "the most Jewish documents of our time", a perspective much amplified by academic exegetes in the wake of the Holocaust. But such suggestions bemused Kafka, who once frustratedly wondered to his diary: "What do I have in common with Jews? I barely have anything in common with myself."

Even while Brod was praising his work for its Jewishness, Kafka wrote to Felice, another critic was simultaneously examining its "fundamental Germanness". "Won't you tell me what I really am?" he implored. In later life he learnt fluent Hebrew, read avidly in the Hasidic tales and dreamt of emigrating to Palestine; yet the word "Jewish" appears nowhere in his work. Again, Kafka seems to float obstinately free of interpretation, slipping from the hands of those who would claim him for a cause.

It is common to say of biography that it sends you back to the work. Stach's book does this in spades, but, importantly for English readers, it also presents new aspects of the work in Shelley Frisch's superb and lucid translations. Many English admirers of Kafka are likely to have read him in dated and occasionally problematic Thirties versions by Willa and Edwin Muir. In her afterword to this book, however, Frisch writes that she has retranslated all the quoted excerpts herself since no standard Kafka edition exists in English. If this constitutes a job application, she would be an excellent candidate for the post. Between them, she and Stach have produced a superbly fresh imaginative guide to the strange, clear, metaphor-free world of Kafka's prose: a prose which, just like the court in The Trial, "wants nothing from you. It receives you when you come and dismisses you when you go."

Kafka: the Decisive Years by Reiner Stach, tr. Shelly Frisch

624pp, Princeton, Telegraph offer price: £14.99

Kafka: the Years of Insight by Reiner Stach, tr Shelley Frisch

624pp, Princeton, Telegraph offer price: £22.95