In tenth-century Baghdad, a physician was asked where to build a new hospital. According to a story told by later writers, he hung pieces of meat in different parts of the city and chose the spot where the meat rotted most slowly. The tale may be legend, but it captures something real about the physician in question, Abu Bakr al-Razi: he trusted tests more than authority.

Inheriting Galen

Medicine in the Islamic world began with the Greek tradition of Hippocrates and above all Galen, the second-century physician whose huge body of work Hunayn ibn Ishaq and his circle translated. Galenic medicine explained health as a balance of four humors and treated illness through diet, drugs, bleeding and regimen. Persian and Indian medicine contributed drugs and methods too. Physicians writing in Arabic organized this inheritance, tested it against their own cases and argued with it.

Al-Razi

Al-Razi (about 865 to about 925), known in Latin as Rhazes, ran hospitals in his home city of Rayy, near modern Tehran, and in Baghdad. He kept careful case records, and after his death his students compiled his notes into a vast medical encyclopedia known in Latin as the Continens. His most famous short work, the Treatise on Smallpox and Measles, carefully distinguished the two diseases by their symptoms and course, a clinical description valued in Europe for centuries. He also wrote a book titled Doubts about Galen, in which he respectfully listed points where his own experience contradicted the master. For al-Razi, honoring a teacher meant testing him.

Al-Razi was also a freethinker whose views on religion and prophecy shocked many contemporaries, and much of his philosophical writing survives only in hostile summaries. He is a reminder that this culture contained real disagreement, not one uniform outlook. His alchemical work belongs to the history of chemistry.

Ibn Sina and the Canon

Ibn Sina (980 to 1037), known in Latin as Avicenna, was born near Bukhara in Central Asia and by his own account mastered medicine as a teenager. He served as physician and minister to several rulers in Iran while writing on nearly every subject. His Canon of Medicine organized the whole of medical knowledge into one systematic work: general principles, simple drugs, diseases of each part of the body, conditions affecting the whole body, and compound remedies. It set out rules for testing a drug, such as trying it on a simple rather than a complicated disease and checking whether its effect was consistent. Translated into Latin in the twelfth century, the Canon was taught in European universities into the seventeenth century.

Critics, then and now, point out that the Canon's very completeness could discourage questioning; its clarity made it an authority to memorize. Later, in thirteenth-century Cairo, the physician Ibn al-Nafis described the passage of blood from the heart through the lungs, the pulmonary circulation, contradicting Galen's claim that blood seeped through tiny pores in the wall dividing the heart. His work was largely unknown in Europe, where the idea was put forward again in the sixteenth century.

Hospitals

The most lasting institution may have been the hospital, or bimaristan, a Persian word meaning place of the sick. Large hospitals appeared in Baghdad in the ninth and tenth centuries and later in Damascus, Cairo and other cities. They had separate wards for different illnesses and for men and women, pharmacies, and sections for the mentally ill. Many were funded by waqf, a charitable endowment that set aside property to support a public good permanently. The endowment deed of the Mansuri hospital in Cairo, founded in 1284, declared that it served rich and poor, residents and strangers, and that patients could stay until they recovered. Hospitals also trained physicians, and in 931 a caliph in Baghdad ordered that doctors pass an examination before practicing.

Fairness demands caution here too. Care for mental illness could include chains and harsh confinement, as it did in most societies before modern times, and humoral theory meant that many treatments did little good or did harm. Yet the idea that a city owed care to any sick person, regardless of religion or wealth, was a striking statement of human worth, and it was written into law through endowments that outlived their founders.

Worked example: Doubts about Galen

Suppose al-Razi treats a patient with a fever, following Galen's rules, and the illness does not run the course Galen predicted. He has three choices: assume he misread the case, assume his copy of Galen is corrupt, or conclude that Galen was wrong. Al-Razi often wrote down the conflict and gave his reasons for his own judgment, while still calling Galen his teacher. Compare a modern doctor who reads a famous study but sees different results in her own patients. The right response is neither to throw out the study nor to ignore her observations, but to record them carefully, check for errors and share them so that others can test them. That habit of documented, respectful disagreement is al-Razi's real legacy, more than any single cure.