Educational books on sex are for sale, though explicit materials are banned, including imperial-era Chinese writings hailed elsewhere as classic erotic literature. Liu started collecting sex artifacts in 1989, three years before he retired from Shanghai University. His trove spans 6,000 years, from fertility idols in jade and ivory to humorous sex toys and statues of mating horses, buffalo and pigs. Some pieces are from Europe, Africa and other Asian countries. Liu's privately financed museum presents them in a setting with a tasteful decor and technical sophistication to rival many state galleries.
Smaller pieces are in glass-fronted wooden cabinets and bigger ones on spotlighted pedestals.
Signs in Chinese and English describe exhibits and their place in history in scholarly language. A locked room holds graphic paintings of sex acts from China, Japan, Thailand and India. Some date to China's Song dynasty of the 10th to 13th centuries. The small turnout suits Liu. He worries that bigger crowds could make authorities look on his museum as a nuisance or hurt its high-minded educational goals.