Refining the Form through the Supreme Yin
"Refining the Form through the Supreme Yin"( 太陰煉形 taiyin lianxing ) is a term of Feminine Alchemy ( 女丹 nüdan ). "Yin" indicates female, and "supreme" means most lofty. "Refining the Form through the Supreme Yin" is a supremely advanced method of refining the form for females. Daoism believes that females are essentially distinguished from males in their born quality. As far as their constitution is concerned, females’ constitution is internally Yang but externally Yin, while that of males is externally Yang outside but internally Yin. In the course of cultivation, unlike males who refine the origin before refining the form, females refine first the form and then the origin. According to the Trigram Figures ( 卦象 guaxiang ) in the Book of Changes ( 周易 zhouyi ), the basic trigram corresponding to females is trigram Kan, which signifies both water and the moon. In ancient times, the moon was the general symbol of Yin things and called "the supreme Yin". Therefore, "Refining the Form through the Supreme Yin" gives directions on females’ cultivation of Inner Alchemy ( 內丹 neidan ) by using the image of the moon. For its content, please refer to the entry "Feminine Alchemy".