Liver and kidney are of the same source

The liver and kidney are intimately related. The relationship between the two has three aspects:

1. The liver and kidney are mutually engendering, i.e., they nourish and support each other. The liver relies on the nourishment of liver yīn to perform its function of free coursing, whereas the regeneration of kidney yīn relies upon the free coursing function.
2. The liver stores blood, whereas the kidney stores essence; blood and essence are both yīn; hence the liver and kidney are of the same source also reflects the notion that blood and essence are of the same source.
3. The ministerial fire present in both the kidney and the liver is traced to a common source in the life gate.