In my work I see many people are attracted to Chinese medicine and spirituality because of their curiosity to the art the art of the bedchamber, Fangzhongshu捧场纹. Some authors even became famous because of that curiosity. I get loads of questions and requests to explain or even show or demonstrate every year, although the last few years peopke seem to understand that practices like these are private, and are not freely shared.

The Art of the Bedchamber is in China as old as the description of medicine theory. In fact medicine theory from early on focused on the wellbeing of women and men in society, the body and the bedchamber. Modern popular literature from van Gulik till Mantak Chia focusses mostly on the spectacle of extreme sexual pleasure, multiple orgasms or long lasting orgasms. In fact that is not part of the art the bedchamber. Within that skill the pleasure principle seems all but absent. plessure is lifted to a whole new level of clarity, that excludes th ecstacy people so often crave for.

The early books are technical manuals on medical sex. Later on because of the influx of Indian Tantra new arts were invented with or without the experience of ecstasy. It became ingrained in neidan practice, as single cultivation… you know, masturbation techniques for male and female… and dual cultivation, which also included sex between men and women. Same sex practices some Daoists made jokes about as belonging to certain Buddhist schools. At the Daoist mount Qingchen in China there is a small fenced street with sculptures of Buddhist monks in a diverse set of copulations with each other and animals. That is a humorous jest, but i guess it doesn't represent the truth.

The art of the bedchamber was redesigned in Tibetan Tantra to help lock the mind inside a particular frame of mental reference. The conscious force of this has to become embodied inside oneself through repetitive practice of the three kaya/states of mental experience.  In Taoist practice Zhengyi schools incorporated sexuality in certain rituals which were also redeveloped inside wizardry and immortality development.

Most people focus on the concept of semen retention for men. The books/manuals speak of that, but without explanation. The semen (jingye精液), (called perfect liquid in Chinese, and not essence/jing as most translations suggest), is seen as a substance that needs to be collected and refined. The thing that is refined though is not the Jingye itself, but its 德 (De), its quality. De is the De of Daode, from Daodejing, the weft of morality. it helps to produce a particular kind of yang阳 (steam). This steam is circulated first through the yang and yin channels and mixed with the weft of the body-jing. For this process ejaculation is not a problem, it is the neidan preparatory practice that is the point. 清修qingxiu is single cultivation or Jing cultivation. It means learning to recognize the De of Jing. If you know the De of Jing, you can discover that qi produces Dao and if there is Dao you see that heaven (tian天) and awareness (shen神) then are the same.
For women the cultivation is on the De of Blood. Once per month she bleeds and takes the De of her own blood, which ofcourse containing her ovum. She does not keep her blood in, although the practice when effective reduces the frequency of menstruation until it eventually stops completely.
In the process of dual cultivation (双修shuangxiu)  the frequency of intercourse is set on the single cultivation. So the men’s cultivation is following the woman’s rhythm. It also means that the man and the women eventually have no more intercourse when the cultivation is constant without the need of intercourse or single cultivation. Ofcourse that is the function of cultivation: to set up permanent awareness, so that all the physiological processes can be monitored. The cultivation then is just a stepping stone. The goal is to understand Dao, because Dao-knowledge is prerequisite to divinize oneself.  Ofcourse in the process you also get to understand the world at large, so it helps to become successful there too. Maybe that is the temptation. It helps to practice to understand this.