Well, spring, stream, river, and sea

The image appears in the first chapter of the Lingshu (Spiritual Pivot), the Jiu Zhen Shi Er Yuan: «所出為井，所溜為滎，所注為腧，所行為經，所入為合，二十七氣所行，皆在五腧也». Where Qi gushes forth is the well; where it trickles, the spring; where it pours in, the stream; where it flows, the river; where it enters, the sea. The twenty-seven Qi, those of the twelve channels and the fifteen collaterals, all circulate through these five points.

The water always runs from the outside in, from the tips of the fingers toward the trunk, whatever the direction of the channel. A commentator quoted in the Zhenjiu Dacheng, Xiang, sums it up this way: «井象水之泉…合象水之歸，皆取水義也». The well is the source, the sea is where the water returns; all the names come from water.

The second chapter of the Lingshu, the Ben Shu (本輸), goes through the channels one by one and names their five points with the same formula. It begins with the Lung: «肺出於少商，少商者，手大指端內側也，為井木». The Lung emerges at Shaoshang, LU11, at the tip of the thumb, and it is its Well point, Wood.

There is one telling exception. For the Heart, the Ben Shu gives not the points of its own channel but those of the Pericardium: «心出於中衝，中衝，手中指之端也，為井木». The Heart emerges at Zhongchong, PC9. This is the same idea the Lingshu states in another chapter: the Heart is the sovereign and is not touched; it is treated through its envelope. The Yang channels also have a sixth point, the Yuan-Source point, between the stream and the river.

The Ben Shu names only the phase of the first point. The Nanjing (Classic of Difficulties), in Difficulty 64, completes the system: «陰井木，陽井金，陰滎火，陽滎水，陰俞土，陽俞木，陰經金，陽經火，陰合水，陽合土». On the Yin channels, the Well point is Wood and the series follows the generating cycle: Fire, Earth, Metal, and Water; on the Yang channels, it begins with Metal. The Nanjing explains this as a pairing of the firm and the yielding: the Yin Well point is the Wood of the heavenly stem yi, and the Yang one is the Metal of geng, its firm counterpart: «庚者，乙之剛也».

Difficulty 63 explains why the Well point comes first: «井者，東方春也，萬物之始生». The well is the east and spring, when all things are born; that is why the count starts there, just as the year starts in spring.

Difficulty 68 assigns each type of point its own field, and this is the basis of many later combinations: «井主心下滿，滎主身熱，俞主體重節痛，經主喘咳寒熱，合主逆氣而洩».

• The well, the fullness below the heart.
• The spring, the warmth of the body.
• The stream, heaviness of the body and joint pain.
• The river, breathlessness, cough, and chills with fever.
• The sea, rebellious Qi and diarrhea.

Difficulty 74 also distributes them by season: «春刺井者，邪在肝». In spring the Well point is needled, because the pathogen is in the Liver, and so on through winter, which is the season of the He-Sea point and of the Kidney.

The best-known rule of the system is in Difficulty 69: «虛者補其母，實者瀉其子». If there is deficiency, tonify the mother; if there is excess, disperse the child. The mother and the child are the phases of the generating cycle, and since each channel has one point for each phase, the rule points to a specific point. The Lung is Metal, and its mother is Earth: its Earth point, LU9, Taiyuan, is its tonification point. Its child is Water: its Water point, LU5, Chize, is its dispersion point. This is where the Atlas's tonification and sedation categories come from.