Practice versus theory: tenth-century case histories from the Islamic Middle East.

Medicine and disease in medieval Islam have thus far been approached through theoretic medical treatises, on the assumption that learned medical texts are a transparent account of reality. A question yet to be sufficiently explored is the extent to which the ideas and theoretical principles they contain were actually carried out in practice. This paper deals with the description of diseases occurring in a tenth-century Casebook (Kitāb al-Tajārib) by Abū Bakr Muhammad ibn Zakarīyā' al-Rāzi (known to Europeans as Rhazes)-the largest and oldest collection of case histories, so far as is known, in medieval Islamic medical literature. Since the author was a prolific medical writer, this study also includes a review of his medical and therapeutic principles dealing with eye diseases, as described in his learned treatises, and a comparison with those therapies actually employed in his everyday practice, as exemplified by the Casebook. The comparative analysis shows that the medical knowledge and the therapeutic advice so meticulously described in theoretical works were not paralleled in the physician's medical performance. On the contrary, it appears that learned treatises served other purposes than determining medical practice.