And yet, even as the Chinese government lets brothels and sex stores proliferate, it continues to wage its decades-long war against pornography and obscenity. Gay and lesbian groups may be largely left alone now, but their members tend to remain closeted with family and friends, a good portion of them in heterosexual marriages. Even as many more young Chinese have premarital sex, traditional ideas die hard. A commentator in the Chinese press recently compared sleeping with an experienced woman to “eating a delicious meal with a secondhand pair of chopsticks.” Every year thousands of women shell out money to get their hymens stitched up ahead of their wedding day — or, if they’re on a budget, insert an artificial hymen that releases fake blood during penetration.

Richard Burger neatly navigates these contradictions in “Behind the Red Door: Sex in China,” showing how lust and prudishness, openness and repression, indecency and modesty can coexist in the People’s Republic. This book is ambitious and wide-ranging. Burger delves into the history of foot binding, the contemporary explosion in HIV and syphilis rates, and the tens of millions of “surplus” men brought on by sex-selective abortion. The author of the Peking Duck, a longstanding English-language blog on China, he also breezes through a series of outrageous internet scandals that rocked the country over the past decade — introducing Muzimei, the bold pioneer who blogged candidly about her sexual encounters with Chinese men, sometimes naming her partners; David Marriott, the British English teacher who did the same with his encounters with Chinese women, sparking a nationalist internet manhunt; and Ma Yaohai, the 53-year-old Nanjing professor of “18 orgies” fame who orchestrated sex parties in the apartment he shared with his mother.

Political motives are not lost on Burger. He gets into the Huxleyan logic behind giving people freedom in their private lives in exchange for limitations on public organizing and activism. (A university professor once told me how in the wake of the Tiananmen crackdown, administrators encouraged students to dance and date. “They wanted them to turn decadent,” he said.) And yet, Burger reminds us, while China’s leaders have loosened the reins, they have not let go of them.

But the book’s greatest strength is in carving out a distinctive story for China — and showing that analogies to the Western 1960s sexual revolution are misleading. The Chinese are not so much shedding the mantle of history, Burger illustrates, as they are rediscovering their country’s past. And that past includes a sexual openness that puts the West to shame.

Beginning as early as the 400s BCE, Daoist sex manuals instructed men, in minute detail, how to prolong ejaculation while bringing a woman to multiple orgasms. This was more about preserving the life force qi — which men accrued by both avoiding orgasm and possessing female partners — than it was about pleasuring the woman. The ideal setup, Burger writes, was for a man “to have multiple partners who were virgins, preferably adolescents between 14 and 18.” Still, this is a far cry from the moralism that would come to dominate the Judeo-Christian world. Even stiff and righteous Confucius never wrote of sex as shameful and thought concubines were permissible in certain situations. And it was Mencius (372–289 BCE) who reputedly said, “To enjoy sex is the desire of human beings.”

That nonjudgmental attitude extended to homosexuality as well. In the Daoist view, sex between men was not so much morally wrong as pointless, as it did not facilitate the accumulation of precious qi. Sex between women, meanwhile, was implicitly condoned. Roughly half of the emperors of the Han dynasty (206 BCE–220 AD) kept young male lovers — a fact we know because imperial scribes dutifully recorded their affairs in works like Biographies of the Emperors’ Male Favorites. Such tolerance prevailed up through the Ming dynasty (1368–1644), when artists produced sex scrolls depicting intercourse between men.

To be sure, Chinese history was not without spells of prudishness. Eras in which the Confucian emphasis on hierarchy and control trumped the Daoist interest in nature were generally not great for sexual freedom. A reactionary swing in the early Ming dynasty brought with it the burning of erotic novels and woodblocks. And yet, Burger shows, the pendulum most often rested on sexual openness. Once the conservative spell had passed, the erotic literature industry again flourished.

It was only in the second half of the 19th century, as Western values seeped into China following the Opium Wars, that puritanism became more entrenched. First, the rulers of the Qing Dynasty (1644–1911) made adultery a serious crime punishable by beating, imprisonment, or exile, and then the early leaders of the new Republic established by the 1911 Revolution continued the repressive trend. Later, in the first half of the 20th century, as Chiang Kai-shek’s Nationalists and Mao Zedong’s Communists battled for control of the country, the two organizations, though diverging on many issues, both conflated modernity and science with bodily restraint. At this time, Burger writes: “A stigma emerged against unwholesome behavior — such as homosexual sex, patronage of brothels, or excessive sexual activity — as being backwards and feudal and not appropriate in the new social order.” Mao took this notion to a new level after 1949, stamping out prostitution and mandating an androgynous, sexless style of dress, even as he himself maintained stables of mistresses.

The irony is that by the time Deng Xiaoping initiated the economic reforms that would usher in sexual openness, licentiousness had been rebranded as Western “spiritual pollution.” The initial government line on HIV was that it had been brought to China by foreigners. Ditto homosexuality; for years, official lore held that China had no gay or lesbian people. So much for Biographies of the Emperors’ Male Favorites.

As Chinese embrace their rediscovered sexual freedom, the notion that carnality is a foreign import is an increasingly difficult sell. Beginning in 1993, the government allowed the establishment of sex stores, provided they maintained an ostensibly medical focus. Employees at Adam and Eve, the first establishment in Beijing, wore white lab coats and counseled customers on cures for erectile dysfunction. Today, China is reportedly home to 200,000 sex stores, and dried deer penis and other traditional medicines have been supplemented by lifelike sex dolls and French maid costumes. Chinese factories now produce around 70 percent of the world’s sex toys — a feat that the public is invited to admire every year at the Guangzhou National Sex Culture Festival. This year’s event, held in early October, drew 250,000 visitors.

Even editors at the once-staid state press have realized that sex sells. For roughly a decade, the website of state news agency Xinhua has featured photo galleries of the sort that might be found only in trashy tabloids in the West: Miss Bikini Global candids, photos of participants in the European Bodybuilding Championships, and shots from a transsexual beauty contest. In October, local mouthpiece Shanghai Daily published a cautionary tale about a couple whose dildo play resulted in a nine-inch sex toy getting lodged in the man’s intestines. The paper quoted a doctor as saying, “People must use sex toys properly and avoid ones that are too big.” This is Chinese public service journalism in 2012.

Then, too, it doesn’t help that Chinese government officials have been caught in acts that make the dalliances of Eliot Spitzer or Dominique Strauss-Kahn look uninspired. In August, over a hundred photos of three men and two or three women engaging in an orgy ricocheted through the Chinese blogosphere. The images apparently surfaced when one participant took his computer in for repair. It wasn’t long before the internet masses determined that two of the men bore a striking resemblance to Communist Party officials from Anhui province. Nor are central government officials immune: former National Bureau of Statistics head Qiu Xiaohua and former railways minister Liu Zhijun are among those who have been exposed for keeping mistresses — in Liu’s case, 18 of them.

Ultimately, Behind the Red Door is a portrait drawn in broad strokes, not a work of narrative nonfiction. We hear from a few interviewees, including a spunky 43-year-old female sex worker who refuses to copulate with customers who are overly well endowed. But the sites so central to China’s reawakening — the gay bathhouses and seedy karaoke parlors and infamous “mistress villages” — are largely left to be imagined. Nor is this an academic book. Readers looking for footnotes and references will be disappointed, and Burger’s mostly measured and evenhanded tone occasionally slips. A passage on the politics of interracial dating in China reads at moments like a guide for foreign men.

But as an explanation of the dueling forces within Chinese society, “Behind the Red Door” is spot-on. Among the book’s more delicious details is the list of seven categories of sex worker devised by Chinese police in the 1990s. My former downstairs neighbors fall into tier five — falangmei, literally “hair salon sisters” — a trade slightly more desirable, apparently, than walking the street or servicing migrant workers at construction sites. The copious detail with which officials characterized sex work establishments betrays more than passing knowledge of the trade. And yet the list also suggests a certain innocence — a pragmatic approach to sex in a culture where it has been intermittently criminalized but not indelibly branded as immoral, a culture that will never have the same tortured relationship to contraception, or gay sex, or sexual fantasy that we do in the United States. May no one ever again evoke China’s sexual landscape and the Summer of Love in the same breath.