The liver and the kidney share the origin of essence and blood. They tonify each other; kidney water nourishes liver wood and both store the ministerial fire. The conception that the liver and the kidney are of the same origin is mainly manifested in two aspects: 1) Mutual transformation of essence and blood. Located in the lower energizer, the liver stores the blood and the kidney stores the essence. Essence could be transformed into blood and blood could nourish essence. Therefore, kidney essence could tonify and replenish liver blood and also inhibit liver yang; liver blood could nourish kidney essence and also maintain the balance between yin and yang in the kidney. 2) Mutual support and restriction between yin and yang in the liver and the kidney. Physiologically, kidney yin as the foundation of the yin fluids in the whole body could tonify liver yin and restrict liver yang. Pathologically, liver yin and kidney yin often affect each other.