Abu Zayd Ahmed ibn Sahl Balkhi (Persian: ابو زید احمد بن سهل بلخی‎) was a Persian Muslim polymath: a geographer, mathematician, physician, psychologist and scientist. Born in 850 CE in Shamistiyan, in the province of Balkh, Khorasan (in modern-day Afghanistan), he was a disciple of al-Kindi. He was also the founder the "Balkhī school" of terrestrial mapping in BaghdadAbu Zayd al-Balkhi was the first to differentiate between neurosis and psychosis, and the first to classify neurotic disorders and pioneer cognitive therapy in order to treat each of these classified disorders.The Muslim physician Abu Zayd al-Balkhi was a pioneer of psychotherapy, psychophysiology and psychosomatic medicine. He recognized that the body and the soul can be healthy or sick, or "balanced or imbalanced", and that mental illness can have both psychological and/or physiological causes.