Rivers and seas of the body

The Jing Shui opens with the Yellow Emperor's question: «經脈十二者，外合於十二經水，而內屬於五藏六府». The twelve channels correspond externally to the twelve rivers and belong internally to the Zang-Fu organs. Qi Bo's answer is a hydrographic map of ancient China:

• Foot Taiyang, the Bladder: the Qing River (清水).
• Foot Shaoyang, the Gallbladder: the Wei River (渭水).
• Foot Yangming, the Stomach: the sea (海水).
• Foot Taiyin, the Spleen: the lakes (湖水).
• Foot Shaoyin, the Kidney: the Ru River (汝水).
• Foot Jueyin, the Liver: the Sheng River (澠水).
• Hand Taiyang, the Small Intestine: the Huai River (淮水).
• Hand Shaoyang, the Triple Energizer: the Ta River (漯水).
• Hand Yangming, the Large Intestine: the Yangtze (江水).
• Hand Taiyin, the Lung: the Yellow River (河水).
• Hand Shaoyin, the Heart: the Ji River (濟水).
• The lord of the Heart, the Pericardium: the Zhang River (漳水).

The Lung and the Large Intestine, an interior-exterior pair, are the two great rivers of China, the Yellow River and the Yangtze. And the map has its own above and below: «腰以上為天，腰以下為地». From the waist up is heaven, and from the waist down, earth.

The comparison is not merely poetic: the chapter uses it to decide how deeply to needle. The Foot Yangming, the channel that corresponds to the sea, is «五藏六府之海也», the sea of all the Zang-Fu organs, with a large pulse and abundant Blood and Qi, and it is needled deeper and for longer: «足陽明刺深六分，留十呼». The other foot channels descend one step at a time down to the Jueyin, which is needled one fen deep. The hand channels, which receive Qi from closer by, go no deeper than two fen. These are measurements from the ancient technique, not the current one, but they show that the geography served a purpose.

Rivers run to the sea, and the Hai Lun gives the body four: «人有髓海，有血海，有氣海，有水穀之海». Each has its entry points, above and below:

• The sea of food is the Stomach: «其輸上在氣街，下至三里». That is ST30 and ST36.
• The sea of the twelve channels, or sea of Blood, is the Chong Mai: «其輸上在於大杼，下出於巨虛之上下廉». That is BL11, ST37, and ST39.
• The sea of Qi is the center of the chest, 膻中, the place of CV17: its points are around the spine of the neck and, at the front, at Renying, ST9.
• The sea of marrow is the brain: «其輸上在於其蓋，下在風府». Above, it is at the cranial vault, which commentators place at GV20, and below, at Fengfu, GV16.

The chapter describes what happens when each sea has too much or too little, and some of its images are unforgettable. On the sea of Qi: «氣海有餘者，氣滿胸中，悗息面赤。氣海不足，則氣少不足以言». With excess, the chest is full and the face is red; with deficiency, there is not enough breath to speak. On the sea of Blood, which in excess makes a person feel their body is enormous and in deficiency tiny, without knowing what is happening to them. On the sea of marrow: «髓海有餘，則輕勁多力，自過其度». With excess, a person is light and strong beyond their measure; with deficiency, there are vertigo, ringing in the ears, weak legs, failing eyesight, and a desire to stay lying down.

Several points have a sea in their name, and it is not always the one from the Hai Lun. CV6, Qihai, the sea of Qi, lies below the navel, whereas the chapter's sea of Qi is in the chest, at CV17, which is why it earned the alias Upper Sea of Qi. SP10, Xuehai, the sea of Blood, is at the knee, far from the Chong Mai. These are two ways of using the same word: the Hai Lun speaks of the body's great reservoirs; the point names, of places where something gathers.