"Their work is associated with sexual and reproductive health and, most importantly, the administration was the only institute in the capital willing and able to accept the pieces and facilitate the exhibition," explained Ma.
However, he conceded that the exhibits had been subjected to censorship by the administration before going on display.
An administration official surnamed Li said the museum has received tens of thousands of visitors, mainly as part of group tours, although individuals were allowed in the very early days.
Li emphasized that he prefers the name "Exhibition of Sexuality and Reproductive Health", rather than "Sex Museum".
"It was free, but visitors had to be older than 18 and had to make a group reservation before arriving," he said.
Ma added that the museum was actually not fully open to the public and said that most visitors were staff members from the population administration, scholars in related fields, and newly married couples.
"We intended to maintain a low profile and seldom promoted the exhibition because we were not sure whether society was ready to accept it," he said.
"Actually too much attention was not good for it at all," he added, recalling the chaos that reigned when the museum opened in October 2003 and more than 200 people swarmed into the exhibition hall, which only had room for 100.
"A glass pane from a case housing one of the objects was smashed," he said, recalling how the chaotic opening day resulted in the museum closing almost immediately.
Since it reopened in early 2004, the museum has only accepted group reservations.
Historical perspective
By working through the six parts of the exhibition, including sex worship in ancient China, sexual physiology and psychology, ethics and morality, and reproductive health, one can begin to gain a deeper understand of sexual urges from a variety of viewpoints and with a historical perspective, said Ma.
"Through the exhibition I just wanted the general public to perceive sexuality properly and become more open about it as a part of human nature, rather than treating it as a social taboo," he said.
Also, exhibitions of this kind can help to correct widespread public misunderstandings about the nature of sexuality, such as the stigmatization of masturbation and oral sex, and the reasons that cause people to abstain from pursuing quality sex lives, he said.
"Some men with sexual dysfunction simply refuse to consult a doctor," he added.
Chinese society was much more tolerant of sexual practices in the days before the Song Dynasty (AD 420-479), so depictions of sex from that period are much more explicit, according to Ma.
For example one piece, a Stone Age sculpture, depicts a couple engaging in reciprocal oral sex, a practice that "is the same today", he said.
Compared with contemporary attitudes, the ancient Chinese were actually quite open about sex, he said.
Confucius considered sex as simply an intrinsic part of human nature: "Food and sex are the essential desires of human beings," explained Ma, quoting the great philosopher.
The change in attitudes occurred during the Song Dynasty, he added. Human desires, including sex, have been suppressed since then and have gradually become taboo in mainstream Chinese culture.
"That's actually the governing class's method of exercising greater control over its subjects, through the suppression of their natural desires," he noted.
Wang Runguo, a Beijing based journalist, said he was originally appalled by the explicit, if not downright pornographic, exhibits, but was eventually won over.
"That (the museum) was 100 percent worth visiting. I was not sure if I'd learn anything, but I did get to see and understand some things I hadn't before," he added.