Quelle est la Difference (Diagnostics Differentials). Kitab Ma al Fariq aw al-Furuq aw Kalam fi al-Furuq Bayn al-Amrad.

Abu Bakr Muhammad Ibn Zakariya al-Razi (also known bythe West by Rhazes or Rasis, circa 865--925) was a physician, and philosopher who made major and lasting contributions to the fields of medicine, music, philosophy, and alchemy. He was the author of more than 200 books and treatises. He left behind more than 200 books and manuscripts containing extracts from earlier scholars regarding diseases and therapy, in addition to numerous records from his own medical practice. He innovated a lot of theories that contributed to the development of medicine at that time; most of his books were translated into European languages and used in many European universities.
He was known in the fields of both medicine and chemistry and undertook chemical experiments to create medicines to treat particular diseases. He followed a scientific approach in his research using the methods of monitoring and observation, which gave his chemical experiments a special value.