What happened to the work of Roman physician Galen (130-200 AD) in the seventeenth century? Was it rejected as a consequence of the Scientific Revolution? Or did it live on in some way? This dissertation examines these classic medical historical questions by studying the investigation of drug properties by Dutch physicians. Studying Galen’s place in these investigations sheds new light on how his works were interpreted in the sixteenth and seventeenth century. This is essential for our understanding of the Scientific Revolution and the investigation of nature in the Dutch Republic, even though the writings of Galen have hardly appeared in the historiography of Dutch medicine. Paaw’s (1564-1617) lessons of materia medica at the University of Leiden consisted of lectures on Dioscorides (40-90 AD), visits to the academic garden and fieldtrips. He presented them as an integrated whole, teaching both the plants’ medicinal properties and how to identify them. However, the relationship between medicine, botany and natural history in the curriculum were less harmonious than it appeared. In his textbook Institutiones medicinae, Paaw’s colleague Heurnius (1543-1601) made Galenic pharmacology a cornerstone of his description of a methodus medendi, a rational method of curing that united the theory and practice of medicine. The textbook was a product of sixteenth-century academic medicine and focused on three aspects of Galen’s writings on the subject: the different tastes, the faculties of drugs and the way drug properties should be investigated through reason and experience. Drug faculties, the particular ways in which drugs worked in particular parts of the body, received most attention. Dodonaeus (1516/17-1585) and Spigelius (1578-1625) published similar accounts of drug properties. Whereas Dodonaeus, like Dioscorides, considered the investigation of the medicinal properties of plants and their appearance as interconnected, Spigelius described them as separate activities. In their attempts to understand the relations ...