Abu Zayd al-Balkhi

Abu Zayd Ahmed ibn Sahl al-Balkhi was a Persian Muslim polymath of the ninth and tenth centuries who worked as a geographer, mathematician, physician, psychologist and scientist. The article on him places his birth in 850 CE in the village of Shamistiyan, in the Balkh region of Greater Khorasan, and his death in Balkh in 934 CE. He was a disciple of the philosopher al-Kindi, spent eight years in Iraq, and returned to Baghdad later in life before settling again in Balkh. Among the many books ascribed to him are The Excellency of Mathematics and On Certitude in Astrology, and his Figures of the Climates, a set of geographical maps, led to the Balkhi school of terrestrial mapping in Baghdad. He is best remembered for Sustenance for Body and Soul, in which he argued that bodily and mental health are intertwined and distinguished four kinds of emotional disorder: fear and anxiety, anger and aggression, sadness and depression, and obsessions.