	In Muslim countries in the middle Ages, medicine was highly regarded and Doctors held in high esteem. Rhazes (860-932) was a Persian Doctor who worked in the hospitals of Baghdad around 900 CE. He studied medicine at Baghdad where he later became hospital director, teacher and court physician. Along with Avicenna Rhazes was one of the best known medical writers.
Rhazes began to move away from a spiritual explanation for disease towards a system based on observation and diagnosis. He translated some of the works of the Greek Doctors in al Hawi (the comprehensive book). He followed the advice of Hippocrates by observing patients carefully and taking notes. He included many case studies in his books. His methods of observation led him to discover the difference between measles and small pox. This was one of the earliest recorded examples of a doctor being able to identify a specific disease. The al Hawi became one of the most widely read medical books in medieval Europe. His text on ‘small pox and measles’, was still being referred to in the 18th Century when inoculation was gaining popularity as a way of limiting the effects of small pox. Rhazes played a fundamental role in the development of medicine as a science, extending the ideas of Hippocrates by providing a clearer understanding of the causes of disease. He came to be ranked alongside Hippocrates and Galen as one of the founders of clinical medicine.
	By Rhazes : Expounded and commented upon by Gerard de Solo. Translated into Hebrew by the physician Tobiel ben Samuel de Leiria of Portugal. Hebrew manuscript on vellum and paper. Portugal, probably mid-15th century : Ff. [203], 20 x 13 cm.
Rhazes' Works Rhazes wrote two hundred and thirty seven works Of these half were related to medicine. The others dealt with a range of his other interests including mathematics, astronomy, religion and philosophy. His best known medical works were liber continens, an encyclopaedia of medical practice and treatment, and the liber medicinalis ad almansorem, which was a compilation from various sources including Hippocrates, Galen, Oribasius and Paul of Aegina. Rhazes was acclaimed work is the 'Liber de Pestilential' – the treatise on smallpox and measles. It is an original work based on direct observation and experience. He supplies an exact description of the clinical picture of both conditions, as well as differential diagnosis. He wrote: 'The eruption of smallpox is preceded by continued fever, pains in the back, itching in the nose and delirium in sleep. Then acute prickling is felt and this goes all over the body, the cheeks go red and the eyes are inflamed. The patient has a sense of heaviness and discomfort, he sneezes, yawns, feels pain in the throat and chest, and breathes and coughs with difficulty. His mouth is dry and he has a headache, feels sick, restless and troubled. Other signs are fever and marked reddening of the gums. When the pustules appear, care must be taken first of the eyes, then the nose and ears: Very small white pustules coming up in contact with each other, hard and without fluid are dangerous, and if the patient remains ill even after the eruption it is a fatal sign. When fever increases, after the appearance of greenish or black pustules and there is palpitation of the heart it is a very bad sign indeed' Smallpox was known in antiquity, but Rhazes was the first to advocate a clearly defined regime of treatment. The 'al-Mansuri', one of Rhazes many writings consists of ten books and is an encyclopaedic review of medicine. The ninth book, which focussed on pathology was most influential in the West. Enjoying many translations it became the standard source for teaching therapeutics until long after the renaissance, especially as a practical guide for medical students.

Abu Bakr Muhammad ibn Zakaria