司天以地上三阴三阳。奉天六元。然上下不类。而以奉之。未解何义。又不解地上三阴三阳。何以定位。内经未之
发明。请试论之。予前既明六元之着。盛于三阴三阳之定位矣。此六元之正义也。乃于其对。亦必三阴三阳奉之。岂三
阴三阳未有定义定位乎。夫天地之大气涵于宇宙。大概藏于北。生于东。长于南。收于西。则三阴在北。三阳在东。三
阴在南。三阳在西。可知也。在易东北俱为阳方。而此北阴东阳。西南俱为阴方。而此南阴西阳者。要此即两仪四象之
义。所谓天以阳生阴长。地以阳杀阴藏者也。盖气必先藏而后生。此乃静藏之地。故三阴先奠位于亥子丑。而太少厥皆
聚者。所以全乎阴以为藏也。藏而后生。而生必于东。故三阳遂正位于寅卯辰。而少明太皆聚者。亦所以全乎阳而为生
也。至于南离阳位。君火居之。而又总为三阴者。盖巳午未皆长气也。有生则必有长。长者实气也阴也。北阴无以实长。
故三阴亦聚于南。所谓天以阳生阴长者此也。西为蓐收正位。燥金居之。故西为阴方。为成为收。而三阳又居之者。盖
藏物必自下。收物必自上。生物必自下。杀物必自上。且自暑而凉。自秀而实。皆自上而下。上者阳也。而其时之肃杀
者、亦阳也。申酉戌为肃杀之方。故三阳亦聚于此。所谓地以阳杀阴藏者此也。盖天之二气。分为四象。北为阴。西为
阴中之阳。此地之二象。东为阳。南为阳中之阴。此天之二象。而生长收藏之理。备着于此矣。
The Si Tian (Heavenly Sovereign) Qi is received by the Earthly San Yin and San Yang. They obey the Six Yuan (the six climatic factors: Wind, Heat, Fire, Dampness, Dryness, Cold). However, Heaven and Earth are not identical in nature, yet the Earthly Qi is used to serve the Heavenly Qi; I do not understand the meaning behind this. Nor do I understand how the Earthly San Yin and San Yang determine their positions. The *Huangdi Neijing* (Yellow Emperor's Inner Canon) has not elucidated this. Please allow me to attempt a discussion.
Previously, I have clarified that the manifestation of the Six Yuan is prominent in the positioning of San Yin and San Yang. This is the correct principle of the Six Yuan. In the corresponding relationship, there must also be San Yin and San Yang to serve it. Could it be that San Yin and San Yang lack definition and position?
The great Qi of Heaven and Earth is contained within the universe. Generally, it hides in the North, generates in the East, grows in the South, and harvests in the West. Thus, it can be deduced that San Yin is in the North, San Yang is in the East; San Yin is in the South, and San Yang is in the West. In the *I Ching* (Book of Changes), both Northeast directions are considered Yang sectors, whereas here we have Yin in the North and Yang in the East. Both Southwest directions are considered Yin sectors, whereas here we have Yin in the South and Yang in the West. This essentially reflects the meaning of Liang Yi (Two Modes) and Si Xiang (Four Images), namely what is said: "Heaven generates with Yang and lengthens with Yin; Earth kills with Yang and stores with Yin."
Generally, Qi must first store before it generates. This is a place of stillness and storage. Therefore, San Yin first establishes its position at Hai, Zi, and Chou (Earthly Branches representing winter). Shao Yin (Lesser Yin), Tai Yin (Greater Yin), and Jue Yin (Terminal Yin) gather here to fully embody the characteristics of Yin for storage. After storage comes generation, and generation must occur in the East. Therefore, San Yang takes its proper position at Yin, Mao, and Chen (Earthly Branches representing spring). Shao Yang (Lesser Yang), Yang Ming (Bright Yang), and Tai Yang (Greater Yang) gather here to fully embody the characteristics of Yang for generation.
As for the South, the Li trigram belongs to the Yang sector, and Jun Huo (Ministerial Fire) resides there, yet it is generally governed by San Yin. This is because Si, Wu, and Wei months belong to the phase of growth. Where there is generation, there must be growth. Growth involves substantial Qi, which belongs to Yin. The Yin of the North cannot make Qi substantial and growing; therefore, San Yin also gathers in the South. This is what is meant by "Heaven generates with Yang and lengthens with Yin."
The West is the proper position of Rushou (the deity of autumn), where Zao Jin (Dry Metal) resides. Thus, the West is a Yin sector, governing completion and harvesting. The reason why San Yang also resides in the West is that storing things must proceed from below upwards, while harvesting things must proceed from above downwards; generating things must proceed from below upwards, while killing (withering) things must proceed from above downwards. Moreover, the transition from heat to coolness, and from flourishing vegetation to mature fruits, all proceed from above downwards. The upper part is Yang, and the austere and killing Qi of this season is also Yang. Shen, You, and Xu months are the sectors of austere killing; therefore, San Yang also gathers here. This is what is meant by "Earth kills with Yang and stores with Yin."
In summary, the two Qi of Heaven divide into Four Images: the North is Yin, and the West is Yang within Yin; these are the Two Images of Earth. The East is Yang, and the South is Yin within Yang; these are the Two Images of Heaven. The principles of generation, growth, harvesting, and storage are fully manifested here.