In 1763, the young James Boswell finished his “London Journal,” one of the frankest accounts of high and low life in the eighteenth century. The following year, he embarked on a Grand Tour. In a Berlin tavern, he encountered a certain Neuhaus. This voluble personage of thirty-nine, unusually tall, with a dark complexion and affected manners, was an Italian who “wanted to shine as a great philosopher,” Boswell wrote, “and accordingly doubted of his own existence and everything else. I thought him a blockhead.”

The “blockhead” had also been travelling around Europe, although not on a patrician’s leisurely inspection of art and ruins. Giacomo Casanova, whose surname means “new house,” practiced many trades—violinist, gambler, spy, Kabbalist, soldier, man of letters—but his main line of work, he later admitted, was deceiving fools. Many of them were gulls at a card table, though he had recently convinced an elderly marquise, a widow with a vast fortune and an obsession with the occult, that he could arrange for her rebirth as her own son. How would this work? Casanova’s mystically enabled sperm would impregnate her with a male fetus endowed with her soul. A casket of jewels was involved, along with a comely young accomplice posing as a naked water nymph. When his ardor flagged, the nymph’s task was to rekindle it.

Casanova had a sideline, of course, which has earned him eponymous immortality; most of us, I’d venture to say, have met “a real Casanova.” But his conquests in the boudoir, not to mention those in carriages, in bathhouses, or behind park shrubbery, have eclipsed his accomplishments while fully dressed. He translated the Iliad into Italian; he published a utopian novel; he grappled with problems in classical geometry; he traded bons mots with Voltaire. He even charmed his way into the French court, posing as a financier, and sold Louis XV on the concept of a national lottery.

Having earned a fortune as a result, he led a princely life for a while, but lost much of it investing in a silk factory that went bankrupt. Now he was back on the road, hustling other crowned heads. Frederick II of Prussia had received him warmly in Potsdam, though they hadn’t struck a deal. Casanova’s next stop was St. Petersburg, to woo Catherine the Great with a proposal for calendar reform. (Russia still used the old Julian system, which was out of synch with the solar cycle.) As the years passed, though, none of his forays bore much fruit except to enrich his journals, the only treasure he never squandered.

Casanova—a.k.a. Neuhaus, di San Gallo, the Chevalier de Seingalt, and Count Farussi—was a priapic precursor of Zelig. Some of his history can be verified, but much of it seems fantastical. Few of the great diarists among his contemporaries, Boswell aside, bothered to mention him, though police records did. Before there was a Wiki culture, a community of “Casanovists,” amateurs united by obsession, doggedly vetted his writings and established the reality of certain exploits. Yet most of what we know, or think we know, about Casanova is what he tells us in his epic, twelve-volume memoir, “Histoire de Ma Vie” (“Story of My Life”).

Of all his adventures, producing “Histoire” may have been the most brazen. It was also his last. Casanova spent his final years writing for thirteen hours a day, or so he said. He ultimately mislaid or destroyed his sources—the voluminous journals he had shuttled from place to place. His latest biographer, Leo Damrosch, the author of “Adventurer: The Life and Times of Giacomo Casanova” (Yale), is a prolific scholar of the eighteenth century who deftly flags a lie here, deflates a boast there, and corrects errors in chronology. But he sidesteps an essential question that he himself poses: To what extent was Casanova “re-creating the past” rather than inventing it?

Casanova was born in Venice on April 2, 1725. He describes himself as a “gloomy” little boy, “not the least bit amusing,” who suffered from hemorrhagic nosebleeds: “Everyone felt sorry for me and left me in peace; they thought my time on earth would be brief. My father and mother never spoke to me at all.”

His mother was a beautiful actress, Giovanna Farussi, who was a muse of the great dramatist Carlo Goldoni and achieved stardom playing the ingenue in his comedies all over Europe. She was known in the Venetian dialect as Zanetta, and, on the stage, as La Buranella. (She came from the island of Burano.) Acting was then a disreputable profession, and Zanetta’s parents, a pious cobbler and his wife, had been horrified when she eloped at seventeen with a fellow-player, Gaetano Casanova, who was eleven years her senior. His talents were mediocre, according to Damrosch, and he needed a day job to support the family: working with optical instruments.

Giacomo was the eldest of their six children (two of whom, Giovanni and Francesco, became notable artists, the latter a court painter renowned for his battle scenes). Casanova later chose to believe the rumor that his real sire was a nobleman, Michele Grimani, an owner of the theatre where his parents met. One might note that the rogue in literature is often a bastard whose sense of grievance against society drives him to subvert it by seducing its patriarchs’ wives and daughters.

The couple’s firstborn was a year old when they left for an engagement in London, parking him with Zanetta’s mother, who doted on him. Seven years later, as his nosebleeds worsened, she took her grandson to an old “witch” on Murano, who did some hocus-pocus and predicted that he’d soon meet a “charming lady” upon whom his “happiness depended.”

That very night, a woman emerged from the chimney, dressed like a queen, and ministered sweetly to him: “I have always thought it was a dream, unless a masquerade had been staged for my benefit,” Casanova writes (in Stephen Sartarelli and Sophie Hawkes’s translation). He dates “the beginning of my existence as a thinking being” to that experience, which is to say, it marked his birth as a cynic. “Sorcerers have never existed”—the witch’s magic didn’t cure him—“but their power has, for those who have had the talent to make others believe they were sorcerers.” He had glimpsed his vocation.

When Gaetano died, months later, Grimani and his brother became guardians of Zanetta and her children. But the widow turned to another noble friend—Giorgio Baffo, a Venetian senator—for advice on her son’s malady. A change of climate was recommended, so Giacomo was sent to Padua, on the mainland, where the air was healthier.

Casanova never forgave his mother for an exile that his siblings didn’t suffer. “Thus was my family rid of me,” he writes. But he treasured his connection to Baffo: “I owe him my life.” It’s worth pausing to consider what else he owed to a man he called a “sublime genius.” Baffo wrote pornographic sonnets in the Venetian dialect that were admired by his libertine contemporaries and condemned by the Inquisition—a badge of honor that Casanova would one day be proud to wear. A quatrain will give you their flavor:

My cock is so stiff that it hurts;
The glans is tingling and I can’t hold on;
It’s as hard as a bone or an iron spike;
Right now, it’s bursting, right now, it’s spurting.

Baffo accompanied Giacomo and his mother to Padua. On the journey, the boy noticed that the trees seemed to “walk” as the boat sailed along. From this phenomenon, he deduced that “the sun doesn’t move either, and it is we who roll from West to East.” His mother mocked his “silliness,” but Baffo, Casanova later boasted, was amazed: an untutored nine-year-old had intuited a theory of which the Vatican took a dim view, heliocentricity. “Always draw the logical conclusions of your reasoning,” he said, “and let the others laugh.”

Casanova’s intellect was central to his sense of worth, and he believed that it would have been stunted “by the cowardice of credulity” had Baffo not risen to his defense. The emphasis is his, and it stresses a horror that generates the drama in his life and work: of the credulity of fools; of his own as “a perfect dupe” of women; and of blind faith in authority, divine or temporal, enforced by the fear of perdition. Enlightenment Deism shaped Casanova’s philosophy—and helped to rationalize his predations. “Mad are those who think the Supreme Being could ever enjoy the sorrow, pain and abstinence they offer up to Him in sacrifice,” he wrote. “He never gave us anything except for the purpose of making us happy.” But “Histoire” contains the germ of a modern anxiety: that no bond we hold sacred is reliable.

In the course of thirty-five hundred pages, “Histoire” has its longueurs. But the first chapter is a marvel of psychological economy. All the seeds of the narrator’s character are planted there. Children of indifferent mothers grow up to doubt their own existence; they can never slake their voracity for love and approval. The charmless little boy becomes a flamboyant showboater. He dodges abandonment by escaping from attachments. Whenever he feels suffocated, he seeks a new climate.

Giacomo’s stay in Padua was among his longer sojourns in one place. His grandmother rescued him from a vermin-ridden boarding house where his landlady had starved him, and lodged him with a young priest, Antonio Gozzi, whom he would later recall gratefully. Gozzi tutored him in Latin and nurtured his love of study, preparing him to earn a law degree. The clergyman also happened to have a sister, Bettina, a beauty in her early teens. Bettina took charge of the boy’s toilette. She gave him a sponge bath every morning—and his first erections.

Bettina’s trysts with an older swain inflamed Giacomo’s jealousy, we’re told in “Histoire,” and she salted the wound with capricious teasing. One of her schemes involved dressing him as a girl so they could attend a ball together. Androgyny always titillated Casanova; a few years later, in Ancona, he fell deliriously in love with “Bellino,” a young soprano of uncertain gender. Unlike Venice, the Papal States barred women from their stages, so the aspiring divo—a poor man’s daughter—was passing as a castrato with the help of a prosthetic penis.

In 1742, at sixteen, Casanova defended his thesis at Padua’s ancient university, having learned more about vice from his classmates than he had about law from his professors. He returned to Venice with a doctorate but also with a penchant for delinquency. Eventually, Zanetta, who was performing in Warsaw, called in a favor. She arranged for her wayward son to become the private secretary of a Franciscan monk who had, through her machinations with the Queen of Poland, been appointed to a bishopric in Calabria.

Casanova gaily set off for southern Italy, expecting to live well there. Instead, he found himself in a squalid backwater among “animals.” After three days in the bishop’s service, he decamped for Rome. Stopping in Naples, he met an aristocrat who was also named Casanova and convinced him that they were related. His namesake endowed him with a costly wardrobe.

“Histoire” doesn’t shy away from the fact that the author’s liaisons with older men were often transactional. Rome, he dryly notes, “obliges the whole human race to turn pederast, but won’t admit it.” Yet one of his most memorable seductions took place there. His lover was a married woman, Donna Lucrezia Castelli, and their clandestine fornication, some of it alfresco, produced a child. Casanova wouldn’t discover the existence of his putative daughter Leonilda for some eighteen years, at which point he fucked her mother while she shared their bed. A decade later, he knocked Leonilda up as a favor, he claimed, to her impotent husband. Incest, he suggests, is a consummate delight: “I have never been able to conceive how a father can tenderly love his charming daughter without at least once having slept with her.”

Plotted on a map of Europe, Casanova’s advances and retreats resemble Napoleon’s. In the course of his travels, Damrosch writes, he covered forty thousand miles. At twenty, he was back in Venice from Corfu, having served in the Venetian Army. Without any glamorous prospects, he played the violin at weddings and at the theatre where his parents met. Shortly thereafter, though, he was forced to flee La Serenissima after an alleged rape, not for the last time. He ended up in Paris, where he acquired a manservant and patronized a famous brothel. An Italian friend invited him to the opera in Fontainebleau. Mme. de Pompadour, he claims, took note of him from her box, and he amused her with some off-color wit in his stilted French. One of many erotic discoveries from this chapter of his “apprenticeship” was a teen-age beauty from a family of prostitutes, Marie-Louise O’Murphy. They didn’t go all the way, but Casanova commissioned a miniature of her, which supposedly inspired “Resting Girl,” the famous nude portrait by François Boucher. It captivated the King of France, who added Marie-Louise to his harem.

After various adventures in Prague and Vienna, Casanova returned to Venice in 1753, living in luxury as the “adopted son” of an elderly senator and cavorting with a beautiful nun, M.M., who was herself a licentious prodigy. The Inquisition was keeping tabs on his gambling; on the pornographic poetry he wrote; on his rumored “devil worship”; and perhaps, Damrosch suggests, on his entanglement with a foreign diplomat, the illustrious Abbé de Bernis, his future enabler at the French court, with whom he shared M.M.’s favors.

In July, 1755, without being informed of the charges against him, Casanova was clapped into a rat-infested cell in the Ducal Palace—an infamous attic prison whose metal-plated roof gave it its name, the Leads. No one had ever escaped it, but he resolved to. He improvised a chisel and used his bed to hide the progress of his excavations. But then he was moved to a different cell. As the months passed, his prospects for release seemed to grow dimmer. A fellow-inmate, a monk incarcerated for corrupting virgins, joined forces with him. They bored holes in their ceilings, and, when they had breached the roof, they climbed onto its fog-slicked slope. Casanova nearly plunged to his death after managing to smash a window, but they gained access to a suite of offices. A watchman who discovered them the next day assumed that they were lost revellers. (Casanova had the foresight, he tells us, to have brought a change of clothes: “my elegant coat,” a lace chemise, a plumed Spanish hat.) They exited the palace by way of its grand staircase and hired a gondola that rowed them to freedom on the mainland.

Le Chevalier dined out on this story all over Europe and eventually published it as an illustrated chronicle that made him a celebrity. W. G. Sebald is among the writers who have cast him as a foe of censorship and despotism. He himself, however, casually told an admirer of Voltaire’s that “the Republic of Venice acted justly.” After his banishment ended, eighteen years later, he volunteered as an informer for the Inquisition, plying his base trade under a pseudonym.

The escaped prisoner made a beeline for the City of Light, where, in 1757, he scored his great coup with the French lottery and found himself with a fortune to dissipate. (Gastronomy was one of his expensive passions.) Months later, he met the credulous marquise, and exploited her obsession with the occult. When she finally got wise to his scam, she had him run out of France. He later tried his luck in the London of George III but, unable to speak English, he didn’t have much. He came to grief with an adventuress, and, in 1764, had to flee England to avoid a potential death sentence for forgery.

Next up was Germany, where he failed to impress Boswell or the Prussian king. His courtship of the empress Catherine proved equally unavailing. In Poland, King Stanisław tipped him two hundred ducats for reciting Horace—one of Casanova’s favorite party tricks—though he subsequently ordered him to leave Warsaw. (His misdeeds in Paris had caught up with him.) Florence expelled him on suspicion of cheating at cards. He was run out of Vienna and Madrid.

Two of his siblings were established in Dresden, where their mother, the great Buranella, was an idol in retirement. She and Giacomo had been estranged for decades, yet he claims that she was overjoyed to see him. (He says nothing of his own feelings about seeing her.) She died in 1776, a year after Michele Grimani, and a year before Casanova revisited Gozzi, his old tutor, who was now an archpriest in Padua. The ruined Bettina was living with her brother; marriage to a “miserable wretch” had left her “poor and unhappy.” She died a day after Giacomo’s arrival, as he sat by her bedside.

Age isn’t kind to those who live by their charms. At sixty, Casanova was forced by destitution to accept a modest sinecure as the librarian of a castle in Bohemia, owned by a noble admirer who was rarely in residence. He had lost his teeth, and his faithful steed no longer reared at his command. “Luck,” he wrote, had “become a stranger” to him. The servants, irritated by his pretensions, tormented him. So did a lifetime of venereal infections, which was probably what did him in.

In 1789, without an outlet for his mischief and deprived of the nourishment that had always sustained him—the fresh sensations of lust and wanderlust—Casanova consoled himself by embarking on his memoirs. The French Revolution was also just beginning. He died nine years later and was buried in an unmarked grave.

“All great storytellers have in common the freedom with which they move up and down the rungs of their experience as on a ladder,” Walter Benjamin writes. By that definition alone, Casanova is a great storyteller. “Histoire” has all the elements of a picaresque novel, a genre that had come into vogue during his lifetime with the fiction of Defoe, Smollett, and Fielding. The narrator is an antihero with a genius for imposture. Splendor and indigence are equally familiar to him; prudence and shame are equally alien. Men and women of every rank find him irresistible, often to their chagrin. His confidence games exploit the vanities of his age at all the echelons of society and mock the hypocrisies at its core.

Le Chevalier’s manuscript—written in (eccentric) French, the lingua franca of diplomacy, one of his ephemeral métiers—has its own picaresque history. A great-nephew sold it to a German publisher in 1821. The firm commissioned an abridged edition, altered and expurgated for the tastes of a primmer age. Stendhal was one of its avid admirers. Scores of subsequent versions, in multiple languages, compounded the tampering. By the late nineteenth century, Casanova had a cult of devotees clamoring to read the original, but it remained under lock and key, where it barely survived the bombing of Leipzig, in 1943. Two years later, Winston Churchill made a worried inquiry and an Army vehicle was dispatched to evacuate it from the rubble. The complete text was first published in 1960 (the year that a British jury found redeeming social value in “Lady Chatterley’s Lover”). Scholars gained access to the handwritten drafts in 2010, when it was acquired by the Bibliothèque Nationale, in Paris, for nearly ten million dollars. Few military secrets have been guarded as jealously.

Dozens of writers have contributed to the Casanova myth. Lorenzo Da Ponte, who had also been exiled from Venice, lent the old roué some money in exchange for a piece of advice that he regretted not taking: “Never sign your name.” But Da Ponte may already have repaid himself in composing the libretto for Mozart’s “Don Giovanni.” The infamous Spaniard resembles his Italian avatar most of all in his disdain for repentance.

The man who doubted his own existence has achieved an enduring afterlife. Toward the end of the First World War, Casanova inspired a novel by Arthur Schnitzler; a comedy in verse by Apollinaire (who translated Baffo into French); and fervent poetry by Marina Tsvetaeva. Schnitzler’s version embodies a corrupt society in its death throes. Apollinaire’s is a “tender and joyful lover” whose generosity contrasts with the nihilism of Don Juan. Tsvetaeva, whose own sex life flouted taboos, casts him as the hero of two plays—coded critiques of Bolshevik moralism.

Casanova made his film début in 1918, albeit silently. Bob Hope played a Casanova impersonator for laughs in the nineteen-fifties. Dennis Potter serialized his life for the BBC. Marcello Mastroianni’s performance as a ruined debtor fleeing his creditors, in Ettore Scola’s “La Nuit de Varennes” (1982), is probably the most indelible portrait: his gallantry in the arms of a capricious fate—his final and most exacting mistress—redeems his pathos. The protagonist of “Fellini’s Casanova,” released in 1976, reflected the director’s “repulsion” for a character in whom he saw “a meaningless universality.” In the final scenes, Casanova makes love with a mechanical doll.

Any life of Casanova has to compete with his memoirs, a masterpiece of reportage. His prose has the freshness of a live transmission. He was writing from the front lines of a secular revolution—one still being fought—for the principle of personal freedom. Despite paying lip service to religion and supporting the ancien régime (low-born upstarts are often the staunchest defenders of class privilege), he ran that principle past every obstacle of law or conscience to its end zone: the goal of unbridled pleasure whatever the cost to others or to himself.

In that regard, the memoirs represent Casanova’s ultimate seduction—of the reading public. Stefan Zweig calls them an “erotic Iliad” that “is hard for a man to read . . . without envy.” The eminent French historian Chantal Thomas, the author of “Casanova: Un Voyage Libertin,” contemplates him more coolly. His prowess as a “fucker” doesn’t interest her—the voluptuous pleasure he gives her comes from his language. Lydia Flem, a Belgian psychoanalyst, mounts an enamored defense of Casanova as “The Man Who Really Loved Women,” depicting him as a proto-feminist.

Damrosch’s biography condenses a vast trove of Casanoviana into a well-researched, four-hundred-page narrative that is most engaging on its subject’s catholic interests as an intellectual and on the milieus he traversed as an itinerant charlatan. But this is a life for a #MeToo-era readership, and the book’s first paragraph posts a trigger warning: Casanova’s “career as a seducer . . . is often disturbing and sometimes very dark.” In one column of Damrosch’s ledger are the “mutually gratifying encounters” that “helped him to write eloquently about sexual experience.” The other column quivers with outrage. Late in his career, a spunky girl slugged Casanova in the nose when he climbed into her bed uninvited and reached for her crotch. “He fails completely to recognize how appalling his behavior was,” Damrosch writes. “That fist to the face had been a long time coming.”

No doubt it had been. Some of Casanova’s paramours were bawds who used him for their own ends, and one such humiliation drove him to attempt suicide. Others were wives in loveless marriages or nuns whose parents had stowed them in a convent. (Depraving a willing novice excited him supremely, especially if she was a lesbian.) Unlike Don Giovanni, who deceived women to ruin them, Casanova thought of himself as their erotic benefactor, and if we take him at his word—we rarely have theirs—he may sometimes have been. But he bought a Russian “slave” for sex whom he resold. As a violinist in Venice, he joined in a gang rape, then claimed that the victim was grateful. Returning to a port he had once passed through, Casanova met a local doctor who thanked him effusively for making his fortune—by sending him fifty patients with the clap.

And then there are “les petites filles.” Damrosch says that Casanova was more of a Humbert Humbert than a Lewis Carroll—that “what attracted him was rosebuds turning into roses.” Still, even his libertine friend the Prince de Ligne noted archly that “little girls, above all, fill his head.” He blithely deflowered pubescent virgins, some of whom were sold to him by their mothers. Chantal Thomas describes the games he played with them: “He undresses them, examines them, caresses them, takes them on his knees, makes them touch his sex,” and is entranced with their “mechanical docility.”

In her view, Casanova needed to identify with the “naïveté” of his victims—“their incomprehension of wrongdoing.” This delusion protected him, she theorizes, from “any insinuation of guilt” that would spoil his pleasure. But the only thing that ever spoiled his pleasure was frustration. One of the mothers who had pimped their daughters out to him complained to the authorities. Her terrified child had resisted his assault, so in a fury he had thrashed her with a broomstick. Yet Casanova raged at her gall. “I broke neither her arms nor her legs,” he protested, “and the girl kept her detestable flower.”

“Histoire” is a saga of wrongdoing from beginning to end, but Casanova indicts himself on every page, often consciously, so condemning him seems superfluous. “As my memoir advances,” he told a correspondent, “I am increasingly persuaded that it is fit to be burned. . . . The ‘Cynicism’ invested in it is outrageous.” In a subsequent letter, he calls himself “a detestable man.” All the same, he had concluded, “you wouldn’t believe how much all this amuses me. I have realized, ‘without blushing,’ that I love myself better than I love anyone else.”

Casanovas tend to swear that they really love women. Did Giacomo? Never more than his freedom, he admits, and not so well as “the glory conferred upon literature.” He writes, “What kept my passion for M.M. always at the same intensity was the fact that I could never have her without the greatest fear of losing her.” Elsewhere, he admits that “love is nothing beyond a more or less lively curiosity.”

To love people is to care about what happens to them, and while Casanova occasionally hooked up with an old flame, their reunions were typically accidental. Whenever he was flush, he pampered his women with jewels and finery; he endowed his water nymph with enough capital to assure her an income; he could be magnanimous to despoiled maidens even when he hadn’t done the despoiling, arranging for secret deliveries. One of his publications was a pamphlet rebutting the work of two anatomists from Bologna, who, Damrosch writes, “claimed to have proved that feminine thought originates in the uterus, and is therefore irrational and literally hysterical.” Gender differences, in Casanova’s view, “are due entirely to education and social conditioning.”

Casanova’s descriptions of consensual sex are artfully graphic without being lewd, balletic in their pacing and naïve in their vanity. Once a woman has satisfied his desires, and he hers (some neophytes need lessons in anatomy), they talk for hours, and he listens raptly. Each paramour is unique to him—fleeting but exquisite, like a rare butterfly. There is only one he will never get over, who etches her mocking adieu in the windowpanes of an inn with a diamond that he has given her: “You will also forget Henriette.” Henriette’s great distinction—besides her breeding and her finesse, in every way superior to his—was to have dumped him. Her abandonment, like his mother’s, grieved him forever.

We live in an age of militant antipathies. Its criteria for judgment are stark. Is a character good or bad? Is a work of art edifying or corrupting? Does it have a redemptive arc? “Histoire de Ma Vie” certainly doesn’t, despite its motto, borrowed from Cicero: “He knows nothing who does not profit from what he knows.” Nor does its narrator evolve: he’s a puer aeternus. But the unregenerate knaves of literature, from Milton’s Satan to Philip Roth’s Mickey Sabbath, are compelling to us as demons precisely because they’re so human in their contradictions. Casanova deserves a place in their pantheon. Whether he invented the past or re-created it, his memoir possesses an incurable reality that still speaks to our own. ♦