Baker has written three previous books, including In Extremis: The Life of Laura Riding, a Pulitzer finalist, and The Blue Hand: The Beats In India. The latter book had been completed but not yet published when Baker, searching for a new subject, stumbled across Jameelah’s papers in the New York Public Library’s Manuscripts and Archives Division. “[I]t was the dissonance of a lone Muslim name, among the commonplace Jewish and Christian ones, that waylaid me,” wrote Baker. Inside the archive’s boxes, she found Jameelah’s books, her impressive early artwork—she had briefly studied with George Grosz at the Arts Students League—and, most important, a trove of letters that seemed to map out their author’s bizarre journey.

But as Baker would discover, Jameelah was an utterly unreliable narrator, and her letters were often deliberately misleading. As a biographer who relies on archives, Baker grew increasingly unsettled as she realized just how untrustworthy the record Jameelah left really was. “That was really devastating to me—it made me realize how much faith I have in archives to be truthful,” Baker says over brunch in Fort Greene, Brooklyn, where she lives with her husband, the novelist Amitav Ghosh. “And of course that’s ridiculous. People lie in letters all the time.”

Her challenge, then, was to construct the book in a way that mimics her own process of discovery. To do so, she adopted a daring, unconventional narrative method—just how unconventional isn’t clear until the very end. Some readers will object when they realize the liberties she has taken with some of her sources, but her approach succeeds in creating a hall of mirrors that forces the reader into constant reassessments. “The form of the book is where the meaning is,” Baker says. “This is really about making narrative sense of a life.”

Not that Jameelah’s life ever makes complete sense. Growing up in the 1940s and 1950s, Peggy Marcus was an awkward, outcast, agonizingly sensitive girl haunted by the legacy of the Holocaust. Like another semi-famous Jewish convert to Islam, Lev Nussimbaum—subject of the best-selling The Orientalist—she initially lionized Arabs out of a sort of Zionist pan-Semitic solidarity. “I am convinced that the Jews and Arabs will cooperate and together create a new golden age such as occurred in medieval Spain,” she wrote at one point.

Of course, that didn’t happen, and the wars that followed Israel’s creation drove her to despair. Partly, like other Jewish critics of Israel, she recoiled at the chasm between her parents’ civil rights liberalism and their anti-Arab racism. “At Smith College, Mother learned to abhor race prejudice,” she wrote. “Not only does she believe that Negroes deserve complete equality of opportunity, she also feels that social intermingling is acceptable and to be encouraged. … So why are the Arabs any different from Negroes?”

In some ways, Jameelah seems like the archetypical self-hating Jew, someone whose qualms about Israel barely mask darker and more destructive impulses. But this doesn’t explain why she didn’t simply become a radical leftist—a natural trajectory for an alienated girl like her. That’s where religion came in. As a girl, Jameelah had a fierce spiritual hunger, which Baker sees as something distinct from mere neurosis. In her assimilation-minded, Ethical Culture family, such impulses had nowhere to go. “There was no language to describe what she was going through, which was a spiritual crisis,” says Baker. “She had a huge desire for a religious life.” Had Jameelah’s parents sent her to a rabbi instead of a shrink, Baker suggests, things might have gone very differently.

And yet, reading the book, one wonders where the line between spiritual crisis and nervous collapse really is. As The Convert proceeds, the extent of Jameelah’s mental instability becomes increasingly clear. By the time she sails for Pakistan, she was barely functional. Her exasperated parents had cut her off, and she couldn’t support herself. Unattractive and terrified of sex, she had little prospect of ever finding a husband. So, when the Pakistani cleric Mawlana Mawdudi invited her, a Muslim sister marooned among the infidels, to join his family, it was a lifeline.

Jameelah had corresponded with a number of prominent Islamists, including Said Ramadan, the son-in-law of Muslim Brotherhood founder Hassan al-Banna, and Sayyid Qutb, the intellectual grandfather of political Islamism. It was Qutb who suggested she write to Mawdudi, the founder of Pakistan’s Muslim revivalist party Jamaat-e-Islami. He was impressed by the clarity and intelligence of her prose and by the zeal behind it. Thinking little of the West and less of Jews, he was easily convinced that her wicked family had cast out their virtuous daughter for no good reason. His shock on meeting the difficult, opinionated, and erratic woman he’d asked into his household was, apparently, profound. So was Jameelah’s realization that even in the idealized community of the faithful, she didn’t fit in.

Still, they kept her. Unlike her own family, Mawdudi and the people around him took care of Jameelah. He had “given her another chance to make a life, a not insignificant gift and perhaps a greater and more profound indictment of the West than anything to be found in his books,” Baker writes. Jameelah eventually became the second wife of one of his associates, and from the safety of purdah, she churned out influential books and articles denouncing Western decadence and celebrating jihad and martyrdom. In exchange for giving up her unwieldy liberty, she found a secure place in the world. And that, of course, is the promise of conservative social orders that value group cohesion over individualism. “There are some people who really can’t deal with too much freedom,” says Baker.

There is, paradoxically, a strong streak of American arrogance in the way Jameelah set herself up as the arbiter of true Islam. In their book Makers of Contemporary Islam, the scholars John L. Esposito and John Voll quote her attacks on Islamic reformers, who she describes as “the mediocre end-product of their circumstances … the result of an overwhelming sense of inferiority which engulfed the East after its humiliating capitulation under the feet of the imperialist West.” Though she was an outsider and a woman, she felt no compunction about dismissing scholars and politicians who’d spent their lives grappling with Islam. This blithe sense of entitlement was itself a result of the imperialist West, though Jameelah seemed oblivious to the irony.

The woman who emerges from Baker’s book is not likable. She is shrill, manipulative, and prudish, though there are glimpses of another, softer, less dogmatic person in the letters she wrote to her parents over the course of three decades. For Baker, trying to inhabit Jameelah was a painful process, and her opinions about her subject remain in flux.

“I was close to a nervous breakdown for a large part of writing this book,” Baker says with a laugh that suggests she’s not being entirely hyperbolic. Jameelah mostly stopped writing in the 1980s, but—at the risk of giving away one of the book’s surprises—Baker eventually discovers that Jameelah is still alive. She’s started sending Jameelah books, most recently the Israeli novella Khirbet Khizeh, about the expulsion of Palestinian villagers during Israel’s creation. They’re not friends, exactly—in fact, Baker found being in the same room with her nearly unbearable. But their lives are now intertwined. “I think I’ll always probably be arguing with her,” Baker says.

On April 15, 1962, Hannah Arendt sent a brief personal note to William Shawn, the editor of The New Yorker, thanking him for some flowers he had sent. It had been a rough winter for the political philosopher: Her husband, Heinrich Blücher, was suffering from a brain aneurysm, and Arendt had developed a severe allergic reaction to antibiotics she was given to treat a cold. Then, in March, a truck had plowed into a taxi she was taking through Central Park, resulting in a concussion, hemorrhages in both eyes, broken teeth, and fractured ribs. Nevertheless, in her note three weeks later to Shawn—who had assigned her to cover the trial of Adolf Eichmann in Jerusalem a year before, and was still awaiting her copy—Arendt sounded almost chirpy. “I am much better,” she wrote, in her blue-ballpoint cursive, spidery and cramped on cream-colored stationery, “and on the point of going back to work.”

Five months later, she was done. On Sept. 19, a sheaf of onion-skin pages arrived at The New Yorker’s office at 25 West 43rd Street, with the title, “Eichmann in Jerusalem: A Report.” The manuscript was sent over to the typing pool, where it was copied onto heavy yellow bond, double-spaced, and then returned to Shawn for editing.

Meanwhile, a carbon copy was delivered to Arendt’s publisher, Viking Press. A lightly edited version of her manuscript was published as a book in May 1963 under the same title she’d picked for the New Yorker articles that were published in February and March but with the dramatically enhanced subtitle “A Report on the Banality of Evil.” The book, with revisions, has remained in print since. But it never reflected Shawn’s changes to Arendt’s draft, which was serialized in five issues of the magazine. So while The New Yorker remains almost reflexively associated with “Eichmann in Jerusalem,” the text that most people have in mind when they talk about Arendt’s report is not, in fact, the one that appeared in the magazine.

The Shawn typescript, cluttered with pencil marks, is now held with the rest of The New Yorker archive at the Manuscripts and Archives Division of the New York Public Library. His major cuts and alterations to Arendt’s original are striking in their consistency: Almost all of them involve Arendt’s asides about the contemporary Jewish community and its handling of the trial. Many of the most controversial passages made it into the magazine intact, including her assertion that “if the Jewish people had really been unorganized and leaderless, there would have been chaos and plenty of misery but the total number of victims would hardly have been between five and six million people.” But the final magazine text is in some ways less provocative, more streamlined, and—unsurprisingly, given the precision of The New Yorker’s legendary copy editor Eleanor Gould—more polished than what’s in the book.

In one sense, Shawn was simply exercising his preference for straightforward structure and well-modulated language: The sections cut from the magazine, especially near the beginning, are generally asides that distract the reader from the central focus of the Eichmann narrative. In some places, he reined Arendt in, softening her claim that Hitler was, in 1935, “admired everywhere as a great national statesman” with a judiciously placed “almost” before “everywhere.” But the cuts also reflect Shawn’s aversion to what Irving Howe, in his criticism of Arendt in Commentary, self-deprecatingly described as the “grubby” polemic of the little intellectual journals. (Ben Yagoda, in his New Yorker chronicle, About Town, noted that Arendt went to Shawn for the assignment on the advice of her friend Mary McCarthy only after Norman Podhoretz told her Commentary couldn’t afford to send her to Jerusalem; given that Podhoretz responded to Arendt’s finished piece with a scathing review subtitled “A Study in the Perversity of Brilliance,” one can only imagine that the final product would have been quite different had Arendt been writing for him.)

Arendt doesn’t appear to have fussed over the cuts. “She did not like to look at things, or go back to things,” explained Jerome Kohn, Arendt’s former research assistant and now her literary executor. “What she gave to Shawn she left in his hands, and what she sent to the publisher, she left in theirs.” She did, however, send in corrections, and requested multiple sets of galleys during editing. “It would make things easier for me,” she wrote to Shawn on Sept. 30, 1962. After the first installment of the series was published, the following February, she wrote to chastise Shawn for an error she had found in the text concerning the date of Yad Vashem’s establishment. “This is an error,” Arendt wrote, noting she had spoken to the fact-checker, William Honan, who went on to be a culture editor at the New York Times. “This is not very important but it confirms my conviction that no dates or facts provided by your checking department should be inserted unless they are checked and approved by me.”

The date of Yad Vashem’s founding turned out to be the least of it, of course. According to Arendt’s biographer Elisabeth Young-Bruehl, Shawn cabled Arendt on March 8 to advise her of the response to her piece: “People in town seem to be discussing little else.” A few days later, on March 13, she replied that she had begun receiving angry letters. “Now the Jews know that enemy No. 1 is not ‘the German’ and the Germans agree that enemy No. 1 is not ‘the Jew,’ it is me,” Arendt wrote, in a letter held at the Library of Congress. “This, to be sure, is an exaggeration and your checking department would not let me get away with it.”

Things were not always thus. For centuries, Jewish prayer was an oral tradition, said from memory. Even as authoritative liturgies were codified, most didn’t have access to texts. Rather, manuscripts—by definition handwritten and unique—were created for communal use, with myriad variations according to local rites. Some of the wealthiest may have had smaller, private copies, but, for the most part, congregations either chanted prayers from memory or repeated after a cantor. Not until Gutenberg’s invention of the printing press in the early 1450s did books become accessible to a broader public, and for some time they remained a luxury.

But even within the unique realm of early prayer books, the Nuremberg Mahzor, which has just gone on public view for the first time in 52 years at the Israel Museum after a nearly year-long restoration, is exceptional. Completed in 1331 for the Jewish community of Nuremberg, the sumptuously decorated work is not only one of the most comprehensive illuminated Hebrew prayer books ever created, it is also among the largest medieval codices in the world.

Weighing more than 57 pounds, it is made up of 521 double-sided leaves. It includes holiday prayers for the entire Jewish calendar; the five books of the Bible known as the megillot, or scrolls; special prayers for lifecycle events like weddings and circumcisions; extensive commentaries; and—its main feature, accounting for roughly 90 percent of the text—over 700 piyutim, or liturgical poems. Moreover, the quality of the scribal work and elegantly embellished panels qualify the text as one of the region’s outstanding manuscripts. While communal mahzorim were also created in Spain, Italy, and other Jewish centers at that time, this monumental format was a phenomenon particular to the Franco-German Ashkenazi region.

Equally impressive is the work’s provenance. The colophon at the back indicates that it was commissioned by a Joshua the son of Isaac and completed on the fourth of Elul in the Hebrew year 5091. It remained in Nuremberg after the Jews were expelled from the city in 1499 and was preserved intact at the municipal library until the early 19th century, at which point, it is assumed, the Napoleonic army excised 11 of its original 528 leaves. More than a century later, the renowned publisher and Hebraica collector Salman Schocken embarked on a quest to reassemble the Nuremberg Mahzor and bring it to Israel. He recovered four of the missing leaves in the 1930s after fleeing Nazi Germany and acquired the rest in 1951 as restitution for assets that had been confiscated from him during the Holocaust. Descendants put it up for auction at Sotheby’s Tel Aviv in 2002, where it carried a $2-3 million estimate but failed to sell. At some point afterward, it was acquired privately by the Zurich-based collectors David and Jemima Jeselsohn, who have given it to the Israel Museum on extended loan. Through February 2010, it will be the centerpiece in the Shrine of the Book, home of the Dead Sea Scrolls.

The restoration, conducted by Michael Maggen, head of the museum’s paper conservation laboratory, focused on rebinding the manuscript and incorporating the four recovered leaves. Overall, the mahzor was in excellent condition. “The decoration and writing looked like they were practically done yesterday,” according to assistant Judaica curator Anna Nizza, who adds that the colors and gold leaf “were amazingly preserved.” The highly skilled scribes who worked on the main text and commentary—identified as Mattanyah and Yaakov, respectively—made almost no errors despite the work’s considerable size. They also masterfully executed simple but sophisticated flourishes while leaving precise blanks around key words for, it is assumed, a Christian artist to subsequently decorate. (Jews were closed out of guilds at that time.)

Rather than iconographic subjects, human figures or narrative scenes that populate other significant 13th- and 14th-century mahzorim, the Nuremberg features 22 illuminated panels highlighting introductory words. These frames are adorned with gold and silver leaf and precious pigments, notably in rich hues of blue and red, and decorated with geometric patterns, as well as foliate motifs and exotic animals, typical of Gothic imagery. The scribes also alternated the size, type and color of the script—between black and red throughout. There is only a single text illustration, of a shofar, next to a line in a Rosh Hashana piyut about the sounding of the ram’s horn. “Unlike their contemporaries,” Nizza explains, “they chose ornamental and non-illustrative depictions, giving the manuscript an aesthetically pleasing and elegant look emphasizing its content while helping the chazan find appropriate prayers during the service.”