Taoist inner alchemy is an important skill that has formed since the Sui and Tang Dynasties by integrating various health preservation techniques such as Taoist breathing exercises, concentration and visualization, fasting, and static skills, as well as the theory of zang-fu organs and meridians in traditional Chinese medicine. It has directly influenced the development of later Taoist theories and cultivation methods. Inner alchemy is regarded by Taoism as the most orthodox immortal cultivation skill, and its main techniques include mental fasting, sitting in oblivion, following the governor meridian, guidance and stretching, breathing regulation, listening to qi, heel breathing, keeping quiet, concentration and visualization, maintaining oneness, fasting, taking pills, sexual intercourse, qi circulation, fetal breathing, external alchemy, and inner alchemy.
Inner alchemy compares the human body to a "furnace and cauldron", and the meridians that circulate in the human body to the channels for inner alchemy cultivation. Under the strict control of artificial mental consciousness, using the driving force of the internal qi in the body, the semen secreted by the human body is cultivated through the whole-body circulation, so that the essence, qi, and spirit are condensed into a "sacred fetus" or "elixir". The school that cultivates this skill is called the inner alchemy school or the Dan Ding school within Taoism.
Inner alchemy is basically completed in four steps. First is the foundation building, that is, taking care of the body and laying a good foundation for the furnace and cauldron; the second is the transformation of essence into qi, also known as the "initial pass", "small celestial cycle", "hundred-day pass", etc.; the third stage is the transformation of qi into spirit, also known as the "middle pass", "October pass", "ten celestial cycle skills"; the fourth stage is the transformation of spirit into emptiness, also known as the "upper pass" or "nine-year pass". It should be noted that the cultivation of inner alchemy needs to be carried out under the guidance of a professional mentor, and it requires long-term persistence and continuous efforts.
At the same time, the effect of inner alchemy also varies from person to person, and it cannot be guaranteed that everyone can achieve the desired effect.
