Shèn (腎) — Kidney / Water

Root of life — water phase, bilateral

Shèn (腎) — the kidneys, paired with the water phase and treated by the Neijing as the root of life (xian tian zhi ben, 先天之本). They store the jing (essence), govern reproduction, growth, and the basal warmth of the body, and rule the bones, marrow, and the lower-back lumbar region. They correspond to winter, the northern direction, the colour black, the salty taste, and the emotion of fear. Lingshu 8 pairs the kidneys with the zhi (志) — will, determination, the steady undercurrent of motivation that survives the wavering of mind and feeling. The kidney-zhi pairing is the substrate of the long-term endurance required for any sustained discipline. We render the rendered point at the anatomical-right kidney landmark (x=0.42, y=0.42), with the canonical TCM understanding that the kidneys are a paired bilateral organ-system; the Neidan tradition further distinguishes left kidney (water proper) from right kidney (ming men, the gate of life, the residence of the yang root) — a distinction not rendered here at the schematic level.

Point 5 of 5 in Five Phases (Wuxing) at the Five Zang Organs