علي بن موسى الرضا
The treatise of Ali al-Ridha includes scientific branches such as Anatomy, Physiology, Chemistry and Pathology when medical science was still primitive. According to the treatise, one's health is determined by four humors of blood, yellow bile, black bile and phlegm, the suitable proportion of which maintains the health. The liver plays an important role in producing and maintaining the required proportions in the body. Ali al-Ridha describes the body as a kingdom whose king is the heart while the (blood) vessels, the limbs, and the brain are the laborers.