Ancient medics extract healing balm from a shrub, in this illumination from an Arab translation of a treatise by the first-century C.E. Greek physician Dioscorides. Referred to by al-Nadim as the “Traveler through the Lands,” Dioscorides described the medical uses of over 500 plants and mineral substances. Although his text was originally written in Greek, it is more commonly known by its Latin title, De Materia Medica. By al-Nadim’s day, Arabic translations of the book (the translation with the illumination at left was published in Samarkand in 987 C.E.) were widely available; the treatise was used as a common reference book by Islamic physicians.