علي بن موسى الرضا
The Ma'mun's palace was a center for philosophical and scientific researches in which many scientific seminars were held. One of the mentioned seminars was on man's body which included the greatest scholars and leaders. Ali al-Ridha, Ma'mun, Gabriel b. Bakhtishu (the physician), Masawaiyh (the physician) and Salih ibn Salhama (the Indian philosopher) were some participants of that medical seminar. The participants were involved in a lengthy discussion about the body makeup and various types of foods, while Ali al-Ridha kept silent. Afterwards, Ma'mun asked him to demonstrate his knowledge of physiology and nutrition and Imam replied: