20. Islamic physicians influenced the manner in which medicines were created
It was another Islamic physician and philosopher, Abu al-Husayn ibn Sina, whose name was Latinized in Europe to Avicenna, who wrote the Canon of Medicine during the medieval period. Enormously influential, the Canon included within its pages recommendations concerning the preparation and testing of medicines. Avicenna argued that all medicines should be as pure as possible, unadulterated with any ingredients which could cause harm or otherwise detract from its quality. It was Avicenna who first proposed what would at a later date be known as clinical trials for drugs, insisting that all new medicines be tested against more than one disease, since their efficacy could vary from one disease to another.
Islamic physicians were restricted by religious beliefs from dissection of human bodies, conducting for the most part research in anatomy on animals. Nonetheless, it was an Islamic physician, known as al-Nafis, who accurately described the circulation of blood in the human body, through the chambers of the heart, and through the lungs. In his description, he contradicted Galen and European physicians who followed his theories, including the belief that blood was created in and flowed from the liver. Islamic medical knowledge entered European thought when the texts were translated into Latin, beginning in Spain, and gradually displaced much of what had been derived from the ancient Greeks.