Al-Razi, known to the Europeans as Rhazes (850 – 923), was at the forefront of Islamic research into medicine. A prolific writer, he produced over 200 books about medicine and philosophy, including an unfinished book of medicine that gathered most of the medical knowledge known to the Islamic world in one place.

This book was translated into Latin and it became one of the backbones of the western history of medicine. Rhazes was also famous for his work on refining the scientific method and promoting experimentation and observation.
His most famous achievement, when asked where to select a location to build a hospital in Baghdad, was to hang meat in locations around the city, and select the spot where the meat rotted the least.
He assumed that the patients would be less likely to suffer from illness and putrefaction of the flesh in this location. He served as the director of this hospital for a large part of his career and performed most of his research that defined Islamic medicine.
Al Razi wrote extensively on the crucial relationship between doctor and patient, believing that they should develop a relationship built upon trust and, as the doctor had a duty to help the patient, the patient had the duty to follow the doctor’s advice.
Like Galen, he believed that a holistic approach to medicine was crucial, taking into account the background of the patient and also considering any ailments suffered by close family, as with modern medicine.
His other great achievement was in understanding the nature of illness, which had previously been described by the symptoms, but Rhazes made the great leap of looking for what was causing the symptoms. In the case of smallpox and measles, he blamed the blood and, as he could not have known anything about microbes, this was a logical statement.
Al Razi wrote extensively about human physiology and understood how the brain and nervous system operated muscles, and only the Islamic distaste for dissection prevented him from refining his studies in this area. (Source: Experiment.resources)