Historian Maximo Terrazos descended narrow stairs into a tomb-like chamber where he says he experienced a sexual awakening of sorts nearly 40 years ago.
Then a 20-year-old university student, he was escorted along with his classmates to a subterranean room marked "Private" in Peru's Museum of Archeology, Anthropology and History to see huacos eroticos for the first time.
Before them were explicit ceramic depictions of sexual acts crafted more than 1,500 years earlier by the Moche, a highly organized, class-based society that dominated Peru's northern coast for 800 years until about A.D. 800.
"For me, it was jolting," said Terrazos, who went on to devote a career to studying sexuality in ancient Peru. "We were the first students who had ever been allowed to see them."
For decades, the huacos eroticos, or erotic ceramics, were locked away from the public, accessible only to an elite group of Peruvian social scientists. Occasionally and reluctantly, they were made available to select foreign researchers from the United States and Europe.
"You couldn't talk about them because they were considered huacos pornograficos," Terrazos said. "They were known as huacos prohibidos because of the taboo imposed by the Christian religion that men have sex only for procreation and that women do not experience sexual pleasure."
Today, exhibitions of these ceramics, running the full gamut of sexual practices, are popular tourist attractions in some of Peru's finest museums.
The Moche ceramics have opened the door to a wide field of study of sexual values in pre-Columbian Peru.
Their study also casts a historical spotlight on centuries of repression by Spanish colonial bureaucrats and Inquisition-era priests bent on extirpating demonic influence from the hearts, minds and loins of the native populace.
In Spanish colonial Peru, huacos eroticos, like most indigenous icons, were smashed to pieces, Terrazos says.
In the 1570s, Viceroy Francisco de Toledo and his clerical advisors were obsessed with eliminating sodomy, masturbation and a common social practice that the Quechua-speaking populace referred to in terms that translate roughly as "trial marriage."
Toledo and the proselytizing priests were aghast to find that not only was homosexuality widely accepted in several regions of the country, but also that the indigenous population placed no particular importance on female chastity and made no prohibition against premarital sex.
One of Peru's most famous colonial-era churchmen, Jesuit Jose de Acosta, wrote in 1590 that "virginity, which is viewed with esteem and honor by all men, is deprecated by those barbarians as something vile," according to "Family Values in Seventeenth-Century Peru," an article by Duke University anthropologist Irene Silverblatt.
"Except for the virgins consecrated to the Sun or the Inca, all other women are considered of less value when they are virgin, and thus whenever possible they give themselves to the first man they find," de Acosta complained.
To put matters right, Toledo ordered that evangelized natives caught cohabiting outside church-sanctioned wedlock receive 100 lashes of the whip "to persuade these Indians to remove themselves from this custom so detrimental and pernicious."
Toledo also issued several decrees aimed at creating near total segregation of the sexes in public.
Violations were punishable by 100 lashes and two years' service in pestilential state hospitals.
Under the Inquisition, brought to Peru in 1569, homosexuals could be burned at the stake.
Sexual mores in 21st century Peru are a far cry from what Toledo and his Jesuit advisors hoped for more than 400 years ago.
Social prohibitions against premarital sex are widely preached and female virginity is exalted, but neither ideal is necessarily adhered to.
Thousands of hourly rate hostels operate 24 hours a day in cities to provide couples with privacy that is unavailable at home.
In working-class households, it is common to see nudie calendars hanging on the same walls as icons of Christ and the Virgin Mary.
The American public first became aware of huacos eroticos in 1954, when Indiana University's Dr. Alfred Kinsey -- author of the famous "Kinsey Reports" on human sexual behavior -- traveled to Lima with his research assistant, Harvard-trained anthropologist Paul Gebhard, to investigate Peru's archeological dirty secret.
Many non-Christian cultures fashioned sexually explicit idols to gods and goddesses of power and fertility.
But the Moche artifacts, Kinsey wrote, were "the most frank and detailed document of sexual customs ever left by an ancient people."
In a 1970 article titled "Sexual Motifs in Prehistoric Peruvian Ceramics," Gebhard wrote that even leading archeologist and collector Rafael Larco Herrera argued -- without supporting evidence -- that depictions of homosexuality in Moche ceramics were symbolic warnings against engaging in such behavior.
Today, Larco Herrera's collection of erotic pottery is the main attraction in a Lima museum that bears his father's name.