How the body worked with medicine.

The body was thought to be made out of four key elements. Yellow bile represented fire. Phlegm represents water. Black bile represents earth, and blood represents air. Fire was produced by the spleen. Water was produced by the lungs. Earth was produced by the gall bladder, and air was produced by the liver. For the body to work, all four elements had to be in balance. Medicine sometimes helped balanced the elements.