The trilogy runs over one thousand pages in the old three-in-one Knopf hardcover I’d picked up secondhand, and I chose to read it slowly, for weeks on end, lugging the hefty, handsome volume everywhere I went. One of its themes is the stubborn power of magic—the bewitching allure of pagan practices in a society that had officially but not wholeheartedly embraced Christianity—and the trilogy did seem to work magical effects: it drew elderly women to me.

Memory tells me that this must have happened seven or eight times, but probably it was more like four. In any event, the encounters were much of a piece. An older woman sitting by me on the subway, or waiting beside me in a line at the Department of Motor Vehicles, or having lunch at a nearby table, would cross the boundary separating strangers in order to volunteer that she, too, had once read Kristin Lavransdatter—a remark accompanied by that special glow which comes at the recollection of a distant but enduring pleasure.

Kristin Lavransdatter was a publishing phenomenon. My own edition was the seventeenth printing—an elaborate clothbound hardcover published in 1973, a half century after the trilogy first appeared in English. The trilogy was a main selection of the Book-of-the-Month Club, where its striking success elicited an unprecedented testimonial: “We consider it the best book our judges have ever selected and it has been better received by our subscribers than any other book.”

Continuously in print for three-quarters of a century, Kristin Lavransdatter is today that rarity of foreign twentieth-century novels: one with competing translations available. Still, it plainly hasn’t captivated later generations as it once did. Though Undset may well be, even now, the best-known modern Scandinavian novelist in the United States, she has been little embraced by academia (which has overlooked Scandinavia generally, apart from its play wrights), and the trilogy is perhaps gradually moving, in the language of the blurb, from “beloved masterpiece” to “cult classic.” When, in 2001, Steerforth Press brought out The Unknown Sigrid Undset, a collection that presented both Undset’s wonderful early book Jenny—a novel set in modern Rome—and a sampling of her letters, its title raised the question whether there is a “known” Undset in this country.

Kristin Lavransdatter’s dense, decade-spanning plot might be summarized as the story of a daddy’s girl who refuses daddy’s choice of a husband and marries for love, with often harrowing long-range consequences. Kristin’s father wishes her to marry Simon Andressøn, an honorable, thoughtful, devoted, and woefuly unglamorous man. Kristin falls instead for Erlend Nikulaussøn, a proud, impulsive, fearless young knight who seems constitutionally unable to steer clear of scandal. After having pledged her love to him, she finds out that Erlend has already fathered children through an adulterous liaison, and when he and Kristin are wed—for the headstrong girl squelches all paternal objections and marries the man of her choice—she is already secretly pregnant. For Kristin, the wedding turns out to be a literally nauseating dissimulation, an unshakable bout of morning sickness as her father gives her away with all the pomp appropriate to a virgin bride. No matter how many children she has under the sanction of holy wedlock—she and Erlend wind up with seven sons—she still feels like a transgressor.

Like the earlier Jenny, whose heroine is a modern Norwegian art student in Rome who disdains a suitor for the suitor’s father, Kristin Lavransdatter is the tale of a scandalous woman. That the trilogy’s readers are meant to regard Kristin sympathetically is but one sign of Undset’s bold and nuanced treatment of sexuality. Although the trilogy’s sex is hardly graphic (almost the only reference to genitalia arises when, in a skirmish, Erlend receives a spear wound to, significantly, his groin), Undset repeatedly lets us know that her heroine is a slave to carnal desires, as when, not long before his death, Erlend discomfits his wife with a casual, jesting reference to those days when her nails dug so deeply into his skin as to leave him bleeding.

In the annals of literary “fallen women,” Kristin Lavransdatter, that twentieth-century/fourteenth-century literary figure, occupies a curious and fascinating place. After they fell, a number of Kristin’s nineteenth-century counterparts were whisked offstage, often to meet a premature end. In the latter part of the twentieth century, many of Kristin’s successors were sexual adventuresses whose exploits were pure and liberated triumphs. Writing in the first quarter of the twentieth century, Undset chose a middle path for her heroine. Kristin never doubts that she has covertly sinned, and the pain of her deceptions remains a lifelong affliction. Even so, her unshakable guilt in no way paralyzes her and she carries on with her life. Throughout the trilogy, Kristin is an indomitable presence in every role she undertakes—mother, mistress of an estate, and even, in her final days, sometime religious pilgrim who chooses to close her life in a nunnery.

Kristin’s painful wedding is both a commencement and a culmination: her life progresses as though her squalid seduction, set in a brothel room obtained by Erlend as a means of protecting their privacy, must forever discolor connubial relations. “The Devil cannot have so much power over a man that I would ever cause you sorrow or harm,” Erlend naively vows after seducing her, yet he has already planted the seeds of distress that eventually will all but destroy his beloved. Actually, their doomed marriage—they eventually part physically, although psychologically they can never sever the tortured bonds between them—is but one of the trilogy’s numerous portraits of domestic discord and blight. At the very close of the first volume, we learn that the marriage of Kristin’s parents is also rooted in deception. Undset’s characters are near-contemporaries of Chaucer’s pilgrims, and they might likewise “speke of wo that is in mariage.”

Undset’s greatest literary strength reveals itself bit by bit, in the way the passions of Kristin, Erlend, and Simon Andressøn play out in all their intricate and lingering aftereffects. Simon’s transformation is particularly affecting. He begins as a promising and enthusiastic suitor of a beautiful young girl, Kristin Lavransdatter; comes to harbor doubts about her devotion; discovers her affair with Erlend and, brandishing a sword, seeks to “rescue” her; in time enters a kind of collusion with the lovers, who convince him not to disclose the affair to Kristin’s father; and eventually marries a homely but wealthy widow, leaving unspoken much of the hurt and regret he clearly feels. The trilogy achieves an exceptional sense of accumulating dailiness, of momentous actions concatenating in all sorts of minute and unexpected evolutions.

The burning lust between Kristin and Erlend feels doubly real, not merely plausible but also proximate. But no less real is that variable, volatile mixture of remorse, shame, loyalty, and fondness which their youthful passion retrospectively stirs. It’s one of the reasons the two of them can never fully part—the memories of a passion so urgent that all other considerations, moral and practical, were subsumed by it. When you enter Kristin Lavransdatter, you enter a marriage, a contract expansively unfolding through time. Disturbingly, fascinatingly, it’s a union of two people who share a proud, combative stubbornness that ultimately undoes them.

When Sigrid’s beloved father died, in 1893, the family found itself in sharply reduced circumstances. She abandoned her formal education while still in her mid-teens and took a secretarial job in an electrical company. She worked there for ten years. She wrote in her spare hours, embarking unsuccessfully on a pair of novels set in medieval times. An influential editor advised her to abandon such projects: “Don’t attempt any more historical novels. You have no talent for it. But you might try writing something modern. You never know.”

The pursuit of “something modern” led to Fru Marta Oulie, a contemporary tale of infidelity, published in 1907 and not yet published in English, and a collection of stories, presumably drawn from life—a number are about Norwegian office workers—followed a year later. The books were respectfully received and sold well. Nonetheless, Undset’s passion for an older world was unquenchable, and in 1909 she published a short novel set in the Middle Ages. (Under the title Gunnar’s Daughter, it first appeared in English in the thirties, and resurfaced as a Penguin Twentieth-Century Classic in 1998.)

The first volume of Kristin Lavransdatter was published in Norway in 1920, with the second and third volumes appearing in succeeding years. The trilogy was quickly translated and just as quickly embraced across the globe. A medieval tetralogy, The Master of Hestviken, which also has at its heart a pair of passionate but troubled and guilt-stricken young lovers, followed in the mid-twenties. In 1928, at the age of forty-six, Undset received the Nobel Prize, chiefly for her medieval epics. She had surmounted every obstacle. In sales, number of translations, significant honors and reader loyalty, Sigrid Undset in 1928 was probably the most successful woman writer in the world.

During the decade of her marriage, Undset published a book of feminist essays. As her translator Tiina Nunnally wryly points out in a helpful introduction to the trilogy’s first volume: “Her written positions were often in direct contradiction to her own life choices.” (Svarstad turned out to be a highly demanding partner, and it was only after she separated from him, in 1919, that her work took off.) For all the upheaval in her personal life, she remained steadily industrious and generous. She donated all her Nobel Prize money to charity and, a decade later, when the Soviets invaded Finland, she sold her Nobel medallion to support a relief fund for Finnish children. When the Nazis invaded Norway, Undset fled to the United States, settling in Brooklyn for a five-year exile, during which she traveled on many speaking tours on behalf of her homeland. She returned to Norway after the war to find her house seriously vandalized. Her health was broken, and she died in 1949, at the age of sixty-seven.

For an English-language reader, much about Undset’s life remains inaccessible, locked away in bibliographies that point toward Norwegian books and articles. This situation was somewhat amended by The Unknown Sigrid Undset, also translated by Nunnally, which includes Jenny, a pair of stories, and—especially welcome—a selection of Undset’s letters that throws welcome light on those apprentice years when the lowly office worker dreamed of a higher life. All of these letters were addressed to Andrea Hedberg, a friend who shared Undset’s literary interests and ambitions. The correspondence, which lasted more than forty years, originated through a Swedish pen-pal club. For any reader who has succumbed to the spell of Kristin Lavransdatter or The Master of Hestviken, there’s a privileged thrill in having these letters available, in hearing an elusive authorial voice, previously filtered through the Middle Ages, speaking immediately of its own concerns, whether in youth (“I’m only happy when I’m alone in the woods”) or in full adulthood (“On the morning of the 24th I gave birth to a son—a big strong boy—5 kilos”).

It’s a voice, one should add, that offers few surprises—insofar as the earnest, fervent, ambitious, far-seeing young electric company secretary is so recognizably, while yet in embryo, the author of the mature novels: Undset was high-minded from start to finish. She spoke freely and unselfconsciously to Hedberg about her coalescing artistic aims. Here is Undset at age seventeen:

Nunnally’s translation redirects our attention. The florid constructions and whimsical quaintnesses have dropped away, and Undset emerges as a writer of spare vigor. Nunnally unquestionably brings us closer to the heart of the book than Archer did. While I have a lingering fondness for the Archer translation—he was the museum guide who first led me to the tapestry—on the grounds of lucidity and authenticity the nod must go to Nunnally, who has surely done as much as anyone in recent years to bring Nordic literature to this country. (She has translated, with fluency and grace, Knut Hamsun, Jens Peter Jacobsen, and Peter Høeg’s Smilla’s Sense of Snow.)

If Archer’s translation scanted the trilogy’s treatment of medieval history, it may thereby have encouraged comparisons to figures less remote in time. Readers may have found in the trilogy’s headstrong and often self-destructive heroine a distant cousin to Vanity Fair’s Becky Sharpe and Gone with the Wind’s Scarlett O’Hara. In Erlend and Kristin’s ill-starred but unstoppable love affair, they may have detected a kinship with Wuthering Heights’s Heathcliff and Cathy. But Kristin Lavransdatter has a dimension these other books rarely aspired to: an encompassing religiosity. Only in the third volume does it grow apparent that the trilogy registers a gradual but inevitable repudiation of the flesh. The appetites of the young girl who lost her virginity in a brothel grow distant and Kristin finally winds up in a nunnery, ministering to others with extraordinary courage and selflessness during a sort of hallucinatory apocalypse—the arrival of the Black Death, which some historians estimate may have wiped out at least half the country’s population.

The growing call of religion renders richly ambiguous the culminating events of Kristin’s life. One might view the trilogy as an accelerating accretion of tragedies, as Kristin’s poor abandoned suitor, Simon, whose love for her is hopeless and perpetual, goes to his deathbed with his faithfulness largely unnoticed or misunderstood by Kristin; as her marriage founders and she loses Erlend to a spear; as illness and blindness and plague pluck her children from her, one by one. The story might also be viewed as the record of a long, hard-won, noble victory, as the passionate teenager who brooks no curbs on her desires, recklessly sowing pain and destruction in the process, decades later renounces the decaying kingdom of the flesh for the indestructible domain of the spirit.

Undset owed an incalculable debt to the anonymous Icelandic sagas of the thirteenth century, as she was the first to acknowledge. When she was ten, she fell under the spell of the longest and perhaps greatest of them, Njal’s Saga, whose elaborate chronicling of violent and implacable feuds overwhelmed her young imagination; she later declared this the “most important turning point in my life.” Kristin Lavransdatter reflects many of the signature traits of the sagas: a matter-of-fact abruptness when unexpected catastrophe supervenes; a tendency to view characters externally, with only occasional ventures into the inner workings of their minds; a wry stoicism in the face of life’s merciless cruelty (Undset notes about Kristin’s mother, who lost her three sons in infancy: “People thought she took the deaths of her children unreasonably hard”); a fondness for characters prone to lengthy brooding silences finally punctuated by shattering admissions, as when Kristin’s mother stuns her husband by announcing, “I’m talking about the fact that I wasn’t a maiden when I became your wife,” or when she declares, “I’ve always known, Kristin, that you’ve never been very fond of me.”

A few such novels may escape this tinge of melancholy. I felt little of it while reading for the first time Don Quixote or David Copperfield or Vanity Fair or In Search of Lost Time, since I never doubted I’d one day return to them. But it’s the fate of most long books never to be revisited. I don’t suppose I’ll ever get around to rereading John Hersey’s The Call, though it’s the only novel I’ve ever read that convincingly situated me in China, or Shimazaki To-son’s Before the Dawn, even if it deposited me deep in rural Japan during the Meiji restoration, or Austin Tappan Wright’s Islandia, although parting from its imaginary Thoreauvian country was a little like leaving the land of the lotos-eaters.

Doubtless many of those readers who adored Kristin Lavransdatter in its original translation never got around to rereading it, and the story faded into a distant glimmering. If the trilogy’s plot embodies an ultimate stripping away of worldly concerns, as Kristin moves slowly but steadily from bodily to spiritual priorities, in readers’ memories a counterpart sort of paring may take place. Again, for most readers, the book’s political machinations—King Haakon and all the rest—probably fled the memory in rapid order, as did any strong feelings about Undset as a prose stylist. What lingered was a feeling of having been transported; what lingered was enchantment. Each time a woman approached me to say, “I once read that book,” she was responding to a literary gratitude so durable it insisted on being expressed to a stranger.

What was another world has now found its way into another world: Nunnally’s new translation, with its cleaner motivations and phrasing, its nuanced balancing of the blunt and the taciturn. Throughout all the tribulations of her life, Kristin winds up being not merely a survivor but an explorer: her hardy soul is on a pilgrimage. It’s heartening to think of a new generation of readers following Kristin’s explorations, and in the process amassing memories so rich they might induce a stranger to approach a stranger and say, “I once read that book.”