Laozi said: "Everything is negative and positive, and anger is rushed to make peace." Everything in the universe is endless, endless, and the fundamental original driving force for change lies in the influence of Yin and Yang. Human beings live in nature, endlessly, endlessly, and it is also the result of the combination of yin and yang. Men belong to yang, women belong to yin, and the law is like the earth, conforming to nature and conforming to yin and yang. Sexual intercourse between men and women is like a cloud on the earth, and the rain on the weather is smooth and natural, as the Book of Changes says: "The density of heaven and earth is the alcohol of all things; Both men and women are good, and everything is transformed. " In ancient humans, sexual intercourse was entirely instinctive, and reproduction was its sole purpose. Because the tail disappears when walking upright, men may have sex with women at any time; And because of the production tools, food began to be rich, free time increased, and female estrus gradually shortened. Since then, sexual intercourse is not only for reproduction, but also for entertainment. This is the separation of sex and reproduction. China people living in China have always maintained a chaotic relationship with nature, and gradually produced natural thoughts and culture. In order to keep in touch with nature and live a long life together with nature, the ancient Chinese people pinned their hopes on the cultivation of sexual intercourse, in order to gain the power of nature, and formed a unique China sexual intercourse, which was gradually supplemented and improved. As the art of sexual love, sexual intercourse is closely related to the development of ancient culture. Under the comprehensive influence of various cultural trends of thought, ancient people practiced sexual intercourse, which not only had the dual purpose of preserving health and preventing diseases, but also had the purpose of reproducing their descendants. (1) Treating diseases, resisting aging and prolonging life In the process of its emergence and development, ancient sexology always runs through a purpose, that is, getting rid of diseases and strengthening the body, being healthy and living longer. 1973 The "seven damages and eight benefits" mentioned in the bamboo slips of Mawangdui Han Tomb unearthed in Changsha have been discussed many times in later generations, such as the Sutra of Plain Woman, the Secret of Yufu, and the Prescription of Medical Heart. As a medical classic, Huangdi Neijing also pointed out that in sexual life, we must master what is seven damages and what is eight benefits. Although there are similarities and differences in the book, they all think that removing seven losses and increasing eight benefits in sexual intercourse will hopefully reconcile yin and yang of the human body and make the body healthy and live longer. Therefore, seven losses and eight benefits have always been the general principle of indoor health preservation. The so-called eight benefits are that in sexual life, there are eight practices that are beneficial to the human body. The key point is to practice guidance indoors, so that qi and blood are smooth and body fluids are inexhaustible. Both men and women have a sense of affection and meaning, and they cooperate tacitly, so as to make up for their interests during sexual intercourse. The bamboo slips of Mawangdui Han Tomb "Talking about Heaven" said: "Eight benefits will govern qi in one day, guide operation, harmonize essence, and practice qigong indoors; Two-day foaming means that body fluid makes sublingual jade liquid; After three days of knowing, you will know the most suitable time for sexual intercourse; Four days of storing gas refers to storing essence; Five-day peace foam means that men and women kiss each other and suck each other's body fluids; Six-day stealing refers to the accumulation of essence; Seven-day temple victory refers to waiting or maintaining victory; It will be done in eight days.