Medicine · a Light

The first book to tell smallpox from measles

Al-Razi's treatise on smallpox and measles sets the two diseases side by side and separates them by what a physician can see and ask: the pattern of fever, the back pain, the state of the eyes, the itching in the nose, how the eruption comes on and how it differs between the two. It is the earliest known clinical account to distinguish them. His management is practical, and much of it is about protecting the eyes, because blindness was the outcome he was trying to prevent. He had no notion of a virus and explained both diseases by the humoral theory of his day, which was wrong. The value of the book is the description, and it was accurate enough that European physicians kept printing it from the fifteenth century into the nineteenth.

Al-Razi · Kitab al-Jadari wa'l-Hasba