Zhouyi Shentongqi laid the theoretical foundation for China's traditional internal and external alchemy. The dominant refining thought is the theory of harmony between man and nature, which combines Yi and old philosophy. It is believed that alchemy should follow the law of the generation and operation of the sun, the moon and the sky in nature, take the two hexagrams of Gankun (Yin and Yang) as the basis, go against the change of nature, seize the merits of nature, return to its origin from the harmony of Yin and Yang, and return to the road of nothingness. As far as Neidan is concerned, we should first examine the essence of human life. As the saying goes, "If you want to cultivate your nature, it will make you live, but if you are late, you should think about it, so you should consider it first. People are endowed with a unique body, and the body is one yuan, which is the essence of Yuan Yunbu, because Qi is the beginning, Yin and Yang are the degrees, and the soul is born. Yang soul, called spirit, soul and spirit are home to each other. " (3) Nihility is the essence of human life, and spirit (soul) is the yin and yang of human body, which is the medicine of alchemy. It is the key to the conclusion of alchemy to take the two hexagrams of "dryness straight" and "quietness" to make qi flow and get the feelings back to nature. Specifically, we should first "build a wall" (based on feelings), firmly plug our eyes and ears, adhere to the "rules", "make our heart return to nothingness, take it for granted and not think about it", concentrate on nothingness, gradually become physically strong, have a moist face, show evil spirits and stand upright, and let internal qi flow around the body. "Lust is like spring, and liquid is like Jie Bing, flowing from beginning to end. (4) The description of internal gas operation experience in practice is quite true; By using the hexagrams to change the principle, the original intention of fire and the changing track of the spirit in practice are expounded in detail. Later generations' internal alchemy theory model, as well as the cultivation rules such as building the foundation and refining the three levels, are all based on this book.

After Wei Boyang, during the Wei, Jin, Southern and Northern Dynasties, external alchemy, persuasion and taking food became popular, while internal alchemy seemed to be hidden and probably existed only in folk esoterics. In the middle Tang Dynasty, Wei Boyang's theory of Inner Dan was further developed. Taoist priests and Luo in Xuanzong of the Tang Dynasty were considered to have made fruitful achievements in cultivating Inner alchemy. Zhang Guo's Tai Shang Jiu Yao Xin Miao Yin Jing applied the philosophy of Yin Fu Jing, and made a clearer exposition of the internal refining rules. Luo He noticed that the inner alchemy described in the Nine Immortals of Dragon and Tiger was influenced by Buddhism. However, until now, the prevailing practice in Taoist circles and society is still to be convinced by the external Dan, while the internal Dan is relatively silent. A Taoist book called Neidan, such as Nine Chapters of Neidan in the King of the South collected by Taixuan Department, says that Neidan is actually a way of gathering thoughts of the Qing school, which is different from Wei Boyang's Neidan, and some convinced Taoist books are also called Neidan. Since the late Tang Dynasty, the confluence of the three religions has become the general trend of China's cultural development. Both Confucianism and Taoism cannot but be influenced by Buddhism, especially Zen Buddhism, which is integrated with China culture. Zhong Liquan's Inner alchemy cannot but be integrated with Zen as the basic development route. Neidan and Zen have a lot in common in the basic principles of practice, that is, "no thoughts". The Collection of Zhong You Missionaries takes the Buddhist term "vacuum" as the focus of practice. There is a saying: "If you think of no thoughts, it is true thoughts, and true thoughts are vacuum, while vacuum is a state, which is gradually moving towards truth and getting out of trance." ⑧ Zhong Liquan disciple Lv Dongbin regards the unity of Zen and Taoism as the basic feature of his internal alchemy theory. It is said that Lu once participated in the Zen master of Huanglong Huiji, and from then on, he believed in Zen and advocated Zen and Taoism. His "Knocking Songs" and others summed up Neidan's program as "double cultivation of life", which means understanding the mind and seeing the nature, and completely explained the so-called mind due to the sea in Zen. Life cultivation refers to refining essence, and qi is the starting path of Neidan. Single repair or single repair is biased, single repair does not repair life, "it is difficult to rob the ghost to be holy", single repair does not repair sex, "like a mirror without treasure", only double repair life can be stable. This so-called double cultivation of life is actually the double cultivation of Zen and Neidan, or learning Zen on the basis of Neidan's cultivation.

Lv Dongbin's thought of double integration of double cultivation and Zen Buddhism has become the basic route for the development of Inner alchemy in later generations. After the Northern Song Dynasty, almost all schools of Neidan originated in Lv Dongbin. Inner alchemy, which combined life and Zen, matured in Zhang Boduan of Northern Song Shenzong Dynasty. Zhang Boduan first wrote the word "Dan" in Wu Zhen pian, which gave full play to the traditional Dan method of Zhong Keke's department. Later, he studied Zen and wrote Zen poems as a sequel to Wu Zhen pian. Five Needles (including the sequel) is recognized as the most influential and highest-level internal alchemy after Zhouyi Shentongqi, and dozens of scholars have made important comments and annotations on it. From Su Shi's list of Taoist cultivation methods, we can find the following phenomena: (1) Su Shi has almost involved all Taoist cultivation methods for thousands of years. Whether it is Dante School or Foucault School, whether it is Inner Dan or Outer Dan; Whether taking medicine or cultivating cinnabar; Whether swallowing body fluids or holding your breath; Whether it is massage or diet; Or cultivate one's morality or cultivate one's morality. Su Shi is diligent in discussion and practice. And these cultivation methods are by no means owned by any Taoist school for a while, and it is even more impossible to communicate and spread among different sects. We can also know from Su Shi's ways of obtaining these alchemy that he has three ways: he has read all the Taoist scriptures. (For details, please refer to He Ziru's Reading in Xitang of Central South Taiping Palace and Reading Taoist Scriptures by Professor Wen Zi Zhan); Obtained from sincere Taoist priests, including the cultivation of some foreign Dan medicines, the treatment of breath, the swallowing of body fluids and so on; From the life experience-reading a hundred books, signing a visa, practicing medicine, etc. Including temperament cultivation, understanding of signing, medical maintenance, and understanding of life. (2) effective massage, handling, fetal interest and other exercises. You saw it with your own eyes. Not only that, as an experienced medical scholar, he used his knowledge and experience to strictly control his daily life, such as diet and daily life, and introduced it to his friends and even political opponents without selfishness, secrecy, reservation and enthusiasm. (3) Su Shi attaches importance to the care of life, but pays more attention to the cultivation of mind and nature, that is, he is more subordinate to the cultivation of "sex" while carrying out double cultivation of life.

Judging from his training attitude, he is a Taoist pragmatist. Su Shi was obsessed with Taoism all his life. Yu's "Su Dongpo's Breakthrough" only talks about the strength of Buddhism, "making him accustomed to indifference and calmness". In fact, Taoism is indispensable. Su Shi used the indifference and purity of Taoism to show his isolation and show a gesture to those in power. "Send Shen Kui to Guangnan" said: "I have been in Huanggang for four or five years. A boat in the smoke ... fame is like magic. I'm really glad that my study is limited. I am ashamed that cinnabar has been paid to you. " Most of Su Shi's Taoist cultivation methods also originated in Sri Lanka. The letter to Liu Yiweng said: "Stone teeth are good, but they don't want to get married, and they are strong by their father and brother. Once caught in the net, he can't kill himself. However, I never forget this heart. Today, I walked away from clothes, and I felt the most guilty. There is no hope of returning. Du Menping's family, except sleeping and eating, is more natural, with a silhouette on his chest and no thorns. Steal the one that can be taught by her husband. " A large number of letters from Huangzhou can prove this.

Open his anthology, it can be said that not only Taoist theories and thoughts, but also Taoist figures, Taoist 36 caves and 72 blessed places can be seen everywhere. When I was a teenager, I thought about fame and fortune (Quyuan Tower) and lamented the life society (Xiandu Mountain Deer). When I was old, I had insight into everything, such as "I have nothing to wait for in my life, I have left this world ... I despise gnats and blow each other." And I have an insight to return to Taoism, such as "Dongpo believes in strange people, is wet in the world, has a way home, and Luo Fu is not a disciple" (with Tao reading Shan Hai Jing XIII). Taoist nouns, figures and Dojo are used more. In the poem "Wang Yi went to Jianzhou to ask for a servant's cursive script", "Ding Ning advised him not to die, and he said that it was accepted by Yan Fang himself ... The river cart was filled with water and flushed with vermilion, but it failed to make it work. Guan Cao seems to be tin and copper. " Quoting Taoist terms such as Fang Tongweng, "Hedong", "Holding water", "Toning the brain" and "Dansha", we "missed" 36 holes in Taoism. Taoist figures are also like Liezi and Zhuangzi in Liezi, who is not evil against the wind and still makes a living in Zhuang (Zhang An Dao Le Quan Tang); "Teacher Dongpo holds the old, and Daohua also tastes a jujube." You Luofu Mountain is a song for my son. "

Su Dongpo lived in Huizhou for four years before and after, but "the stick is floating." He and his son, Su Guo, built a "Dongpo Mountain House" near Gehong's alchemy stove and made an alchemy near it.

Dongpo hoped that he could, like Ge Hong, "hang up the hard work party, abandon the splendor and wealth" and enter the famous mountains for a long life. He admired Ge Hong and said, "Although I hate studying Taoism late, I am ashamed of being young." In a poem to his son Su Guo, he said: "Dongpo's teacher is old and simple, and the original work has long been handed over to his former life." In his dream, Su Shi talked with Ge Hong about alchemy. He wrote a poem: "Dust is refined and empty, and a little merit is accumulated;" According to the night, I remember boarding the dragon, and I am closed to the fog. Develop a danzao without fireworks and point out that there is a faint copper in the world. J sent a message to stop, I am not poor. I thought I was a disciple of Bao Puzi in my last life, and I will still be a teacher in this life. Mr. Li Ling regards it as "the source of the study of internal alchemy" ... The theory of internal alchemy is a key, and the theory of internal alchemy first appeared in Laozi Ming, Immortal Wang Ziqiao Monument and the theory of internal alchemy in the Eastern Han Dynasty. On this basis, he thought, "They should be the true symbol of Inner alchemy. (2) Inner-Dan thought was carried forward by Dongpo, following the Taoist thought of "keeping as one, cultivating as one, managing heaven and earth", "keeping Xuanzang, closing your eyes and looking for Huang Ting", meditating on Huang Ting classics and doing qigong breathing. He also wrote poems with the metaphor of Danfa, leaving many chapters of Neidan, opening a colorful chapter in the history of Neidan, and playing an irreplaceable role in the top-down development and communication history of Neidan at that time. Bai Yuchan was also deeply influenced by Su Shi and regarded Su Shi as his family. Su Dongpo is often called "Broken Immortal" in the poems of Bai Yuchan ancestors, which can be used as a reference for those who know Su Shi. That is, Quanzhen Daoism founded by Wang Sou and Qizhen School of Seven Disciples under Wang Sou's Zushu. Contrary to Nanzong in cultivation, this school advocates putting sex first before life, doing kung fu to get rid of feelings and desires first, keeping one's heart clear, seeing one's own nature clearly, and taking a pure heart as the secret. From then on, I started from the heart, refining essence, refining gas and refining spirit in turn. The Northern School advocates pure cultivation, becoming a monk, abstinence and asceticism. After the Yuan Dynasty, the Northern Sect of Danfa absorbed the theories of Southern Sect and Neo-Confucianism, with Wu Shouyang in the late Ming Dynasty and Liu and Min Yide in the Qing Dynasty as the clearest explanations. Wu Shouyang's Quotations on the Combination of Immortal and Buddhism and Immortal Theory.

Danfa is divided into four steps: building a foundation, first refining qi, middle refining spirit and upper refining spirit. Laying a foundation focuses on refining oneself, that is, refining oneself means making great efforts to understand the scenery, and then refining essence, gas and spirit step by step. Min Yide's Collection of Ancient Books Hidden in the Building in A.D. collected many descriptions of internal alchemy, among which Huang Zhitong, the living are alive, and Yin is? Equal density means that Chen is very fine, and there is a way to start with the meaning of the top door. In the early Qing Dynasty, Changyue Wang, a Taoist priest of Quanzhen in Zhongxing, emphasized that Dan's cultivation should be based on observing precepts, strictly following the order of observing wisdom, and paying attention to ethical cultivation and understanding.

Neidan School refers to Li Daochun's theory which was merged from Quanzhen Daonan Sect in the early Yuan Dynasty. Li summed up the two schools of North and South, and inherited Chen Nan's theory, and divided all the cultivation techniques of Taoism into three categories: side door nine-grade, gradual method three-multiplication and maximum multiplication. The latter two belong to Neidan. The third step is gradual, and the next step is "taking body and mind as a cauldron, essence as medicine, heart and kidney as fire and water, five internal organs as elements, liver and lung as dragons and tigers, essence as true seeds, year, month and day as heat, pharynx and body irrigation as bath, nose and mouth as three essentials, kidney as xuan before and after, and five elements as Dan Cheng". This is the way to live a long and happy life. Zhongcheng takes Gankun as the tripod, Li Kan as the fire and water, black rabbit as the medicine, essence, spirit, soul, spirit and meaning as the five elements, body and mind as the dragon and tiger, qi as the true species, one year's cold and summer heat as the summer heat, water irrigation as the bath, internal and external as the solid economy, the etheric Yuanjiang Palace's fine room as the three essentials, clay pills as the porch, and spiritual mixing as the elixir. AF claims that this is a way to nourish life and can lead to long-term vision. Excellent "take heaven and earth as cauldron, sun and moon as fire and water, yin and yang as chemical machine, lead, mercury, silver and sand as five elements, temperament as dragon and tiger, mind as true species, mind as heat, rest as fire, light as solid aid, subduing inner demons as field battle, body and mind as three essentials, heavenly heart as porch, and emotion as Dan Cheng". AG says it is a good way to prolong life and can prove that fruit is immortal. This Dan method is Bai Yuchan's way of practicing life with Zen. The first ride, "Tai Chi is the tripod, Tai Chi is the furnace, purity is Ji Dan, inaction is the belly, life is lead and mercury, wisdom is fire and water, rage is fire and water, temperament is alloy wood, purity is the bath, honesty is the solid economy, abstinence and wisdom are the three essentials, and the middle way is the porch, the heart is perfect, and it is naturally condensed. Call this the way of top-grade immortals, and the achievement of spiritual practice can be "wonderful in form and spirit, true in Tao." "Ah, this riding method has a strong Buddhist flavor. Li believes that the three-step gradual method is suitable for the cultivation of junior, middle and staff sergeant respectively. Staff sergeant can do it, and staff sergeant with roots can "have sex all the time and die naturally" without repairing his life. People in the middle and lower classes should adopt a step-by-step lifestyle before having sex. Li Daochun's theory of Inner Dan indicates that the theory of Inner Dan in the Southern and Northern Dynasties reached a high degree of maturity through the integration in the early Yuan Dynasty. In addition, since the Tang and Song Dynasties, the Neidan family has emphasized that women's cultivation of Dan should be different from men's according to the physiological differences between men and women, and created a "female elixir" specially for women's cultivation of Dan. Sun Buer, a disciple of Wang Sister-in-law in Jin Dynasty, founded Quanzhen Daojing School, which specializes in teaching female Dan.

There are more than 30 kinds of fairy poems written in past dynasties, such as Fairy Poems and Kun and Fairy. It is generally believed that women's alchemy should start with alchemy, first make the power of "cutting the red dragon" to refine blood and gas, and then refine gas and spirit according to the method of men's alchemy.

Neidan theory has a long history. It was expounded at the end of Han Dynasty and prevailed in the late Tang Dynasty. It absorbs the strengths of Buddhism, Confucianism and medicine, and gradually matures, gradually forming a complete theoretical system and a variety of cultivation methods. Based on the classics such as Tao Te Ching and Yin Fu Ching, it integrates Taoism, Zen, Yi, Confucianism and medicine, forming a unique theory based on the rise and fall of human life, which has a wide influence and inspiration on Qigong, medical care and human science.