PURPORT

The controlling deities of the intestines are rivers, and those of the arteries, the seas. Fulfillment of the belly with food and drink is the cause of sustenance, and the metabolism of the food and drink replaces the waste of the bodily energies. Therefore, the body's health is dependent on healthy actions of the intestines and the arteries. The rivers and the seas, being the controlling deities of the two, keep the intestines and the arteries in healthy order.