Woodcut illustration of the practice known as 'The infant takes form and appears' from Xingming guizhi (Pointers on Spiritual Nature and Bodily Life) by Yi Zhenren, a Daoist text on internal alchemy published in 1615 (3rd year of the Wanli reign period of Ming dynasty).
'The infant takes form and appears' (yin'er xianxing) is a term from Daoist internal alchemy. The Infant (yin'er) is the essence of the kidney. Zhenji, in Pointers on Spiritual Nature and Bodily Life, states: If the cooking time has already been sufficient, and the Sacred Embryo is already rounded, provided the cooking is thoroughly done, the infant will be born. When the ten-month term is accomplished, it will separate from the placenta. Exegetes call this the practice of the body, or the filling of the mysterious portal; it is called the newborn (chizi) or the infant. When the infant moves the embryo and changes the cauldron, it suddenly emerges to dwells secretly in the Qi Cavern.
