The grain deity does not die — Gu means nourishment. If a person can nurture the spirit, then he will not die. Spirit refers to the five zang organs' spirits: the liver stores the hun, the lungs store the po, the heart stores the shen, the kidneys store essence, and the spleen stores will. When all five zang organs are completely damaged, the five spirits depart. This is called the mysterious female — what is said to exist without death lies in the mysterious female. Xuan means heaven; in humans it corresponds to the nose. Ming means earth; in humans it corresponds to the mouth. Heaven nourishes people with the five qi, which enter through the nose and are stored in the heart. The five qi is subtle, forming the five natures of essence, spirit, acuity, clarity, and voice. Its ghost is called hun; the hun is yang in nature, governing entry and exit through a person's nose, connecting with heaven — hence the nose is referred to as Xuan. Earth nourishes people with five flavors, which enter through the mouth and are stored in the stomach. The five flavors are turbid and defiling, forming the six emotions of form, body, bones, flesh, blood, and vessels. Its ghost is called po; the po is yin in nature, governing entry and exit via a person's mouth, connecting with earth — hence the mouth is referred to as Ming. The gate of Xuan Ming is called the root of heaven and earth — Gen means Yuan. The gate of nose and mouth is where the original qi connecting heaven and earth flows back and forth. Continuous as if existing — the inhalation and exhalation through the nose and mouth should be continuous and subtle, seemingly present yet also as if nothing. Use it without exhaustion — when using qi, one should be relaxed and not hurried or overexerted.