The *Dongxuan Jing* (Scripture of the Mysterious Profound) states: "That which has form cannot be without a name; that which has a name cannot escape numerical laws. On a grand scale, such as the Yin and Yang of Heaven and Earth, their ascending and descending movements do not deviate from propriety; on a clear scale, such as the Hun (Soul/Spiritual Aspect) and Po (Corporeal Soul/Physical Aspect) of the Sun and Moon, their coming and going follow their own measures. A deviation of even a millimeter leads to total reversal. If Yin and Yang err or lie dormant, the four seasons will fall into chaos and fail to generate all things; if cold and heat do not alternate, the eight climatic periods will be disordered, preventing the smooth circulation of Qi (Vital Energy). Humans are the most precious among all things, the spirit within one Qi. On a grand scale, humans take imagery from Heaven and Earth, not violating the propriety of ascent and descent; on a clear scale, they model themselves after the Sun and Moon, not disrupting the measures of operation. Actions are determined by time, responses are aligned with numbers. In terms of the Dao (The Way), what distance is there?"

The *Xishan Ji* (Record of Western Mountain) states: "The Great Dao is formless, yet it gives birth to Heaven and Earth. Warmth, coolness, cold, and heat undergo one cycle of interaction per year; if this interaction does not miss its timing, one year follows another. The Great Dao is emotionless, yet it operates the Sun and Moon. The half-moon (Shangxian), full moon (Wang), last day of the month (Hui), and first day of the month (Shuo) come and go once a month; if this coming and going does not miss its timing, one month follows another. The Great Dao is nameless, yet it nourishes all things for eternity. Do not say that because Spring generates and Summer grows, plum blossoms will not be beautiful or chrysanthemums fragrant; do not say that because Autumn harvests and Winter stores, cypress seeds will not mature or pines will not flourish. Because they receive Qi according to time and days, and because of Qi they arise and develop, even ignorant grass and trees are so spiritual. Since humans exist, why not follow nature to nourish True Nature (Zhenxing) and cultivate the physical body? Cranes know the midnight hour (Zi Shi); swallows recognize Wu and Ji days (Central Earth). Responding to Yin, they follow Yang; due to Water, they avoid Earth. Snakes do not cross paths on Si days; orioles naturally emerge from valleys in Spring. Even unthinking birds and beasts are so precious. Since humans exist, why not follow the seasons to nourish Primal Yang (Yuanyang) and store True Qi (Zhenqi)? Alas! Ignorant people, believing their Qi is sufficient, let it leak and dissipate, losing over 810 zhang, causing their Yuan Qi (Primal Qi) to deteriorate over time. How can they know that the great movement of Zhen Qi follows Heaven: in Spring it resides in the Liver, in Summer in the Heart, in Autumn in the Lung, and in Winter in the Kidney. The small movement of Yuan Qi follows the daily cycle: at Zi hour it is in the Kidney, at Mao hour in the Liver, at Wu hour in the Heart, and at You hour in the Lung. The four seasons of Heaven and Earth, the phases of the Sun and Moon, and the Zi-Wu-Mao-You hours of humans correspond perfectly. Winter is Yin. From Yin, Yang arises becoming warm, thus called Spring. Here, Yang is master and Yin is guest. From Yang, more Yang arises becoming hot, thus called Summer. Summer is Yang. From Yang, Yin arises becoming cool, thus called Autumn. Here, Yin is master and Yang is guest. From Yin, more Yang arises becoming cold, thus called Winter. This constitutes the four seasons of Heaven and Earth. Dawn is dark; from Po, Hun arises becoming bright, thus called Shangxian (First Quarter Moon). After Shangxian, Hun is substance and Po is function; from Hun, more Hun arises, called Wang (Full Moon). Wang is bright; from Hun, Po arises becoming dark, thus called Xiaxian (Last Quarter Moon). After Xiaxian, Po is substance and Hun is function; from Po, more Po arises, called Hui (Dark Moon). This constitutes the four phases of the Sun and Moon. Heaven and Earth have 360 days; Sun and Moon have 360 shichen (two-hour periods); humans have 360 acupoints (du). Heaven and Earth have 24 solar terms; Sun and Moon have 24 degrees; humans have 24 shichen. From Zi to Wu is the time when Qi generates, belonging to Yang. From Wu to Zi is the time when Qi declines, belonging to Yin. Yin, Chen, Wu, Shen, Zi, Xu are the six shichen of Yang generation; Mao, Si, Wei, You, Hai, Chou are the six shichen of Yin generation; Jia, Bing, Wu, Geng, Ren are the Yang times of the Five Elements; Yi, Ding, Ji, Xin, Gui are the Yin times of the Five Elements. Chen corresponds to Taiyang (Greater Yang); Mao corresponds to Yangming (Bright Yang); Yin corresponds to Shaoyang (Lesser Yang); Chou corresponds to Taiyin (Greater Yin); Zi corresponds to Shaoyin (Lesser Yin); Hai corresponds to Jueyin (Terminal Yin); Xu corresponds to Taiyang; You corresponds to Yangming; Shen corresponds to Shaoyang; Wei corresponds to Taiyin; Wu corresponds to Shaoyin; Si corresponds to Jueyin. At Wu hour, Kidney Qi interacts with Heart Qi, moving from below upward, which is the time when Three Yang Qi gathers. At Zi hour, Heart Qi interacts with Kidney Qi, moving from above downward, which is the time when Three Yin Qi gathers. Hun is Yang within Yin, its Qi arises at the beginning of Mao; Po is Yin within Yang, its Qi arises at the end of You. Nourishing Yang is not limited to Spring and Summer; the reason Spring and Summer can nourish Yang is that Qi resides in the Heart and Liver. Nourishing Yin is not limited to Autumn and Winter; the reason Autumn and Winter can nourish Yin is that Qi resides in the Kidney and Liver. After the Summer Solstice, True Mercury (Zhen Gong) accumulates in the Jianggong (Crimson Palace, referring to the Heart region); after the Winter Solstice, True Lead (Zhen Qian) accumulates in the Dantian (Elixir Field). When Wood Qi interacts with Heaven's 25 degrees, it is the Xun trigram; Yang interacts with Yang, and one should gather here to form the Great Medicine. When Metal Qi interacts with Lingfu's 25 degrees, it is the Qian trigram; Yin interacts with Yin, and one should refine here to call it the Returning Elixir. To ignite fire for refining the form, it must be before Qi ascends; to gather fire and return to the Origin, it must be during Yin's descent. Refining the form to remain in the world prioritizes Qi, using the times of the mutual overcoming of the Five Elements. Refining Qi to transcend the mundane prioritizes time, utilizing the cycles of the Three Fields (San Tian). Cultivators who see no results do so because they do not gather during prosperous times, do not supplement during declining times, do not condense during scattered times, do not extract during converging times, do not seek during non-existent times, and do not refine during returning times. Not knowing the time of intersection, nor possessing methods of extraction, they waste days and months, seeing no progress of even an inch. How can they compare to the longevity of Heaven and Earth and the solidity of the Sun and Moon?"