Ali ibn Abbas al-Majusi

Ali ibn Abbas al-Majusi, known in the Latin West as Haly Abbas, was born around 930 CE in Ahvaz in the Ahvaz region of Iran, into a family of Zoroastrian origin — his surname al-Majusi referring to this heritage. He flourished as a physician and scholar in the Buyid Emirate, eventually finding patronage at the court of Adud al-Dawla, the powerful Buyid ruler of Shiraz, to whom he dedicated his magnum opus.

His monumental work, the Kitab al-Maliki (The Royal Book, also known as Kamil al-Sina'a al-Tibbiyya — The Complete Art of Medicine), written around 980 CE, stands as one of the most comprehensive medical encyclopedias of the medieval world. In twenty books divided equally between theory and practice, al-Majusi systematically covered anatomy, physiology, pathology, materia medica, and surgery. He was highly critical of his predecessors, noting gaps in al-Razi's clinical focus and Hunayn's theoretical organization, and set out to remedy both.

Al-Majusi made significant contributions to understanding of the circulatory system, describing the pulsation of the heart and arteries with clarity. He offered early insights into what might be recognized as capillary circulation, noting that nutrition reaches the peripheral tissues through very fine vessels. He also wrote remarkably on mental illness, treating conditions now recognizable as depression, mania, and psychosomatic disorders with both physiological and environmental explanations.

He died around 994 CE in Shiraz. The Kitab al-Maliki was translated into Latin by Constantine the African around 1087 CE as the Pantegni and later by Stephen of Antioch in 1127 CE, making it a foundational text in European medieval medicine until it was superseded by Ibn Sina's Canon.