The Four Viscera are to the Kidney, and the Branches and Leaves are to the Root

   Kidney is the "root" of other organs, vital to the human body, which is characterized by the storage of "kidney essence";

     "The four viscera are to the kidney, and the branches and leaves are to the root"  The True Biography of Medical Science by Ming Yu Tuan

   Kidney essence: throughout the whole growth and aging process, is the material basis of the kidney, the source of energy, is the source of power of the human body's various life functions, just like gasoline in the car; Kidney essence loss, will cause a variety of life function decline, resulting in aging, just like a car that will run out of gas, can no longer run normally.

   Kidney essence ups and downs throughout the growth of the old