Margaret Garber

In 1648, J. Marcus Marci of Prague anticipated two chief features of Isaac Newton's celebrated 1672 theory of light and color, namely that colors are inherent to light and that the role of the prism is to separate the rays of color by means of refraction. Furthermore, Marci argued that colors produced by a first refraction are immutable when subjected to refraction by a second prism. This paper argues that the key to Marci's achievement derived from his chymical view of light, which he tested by means of prism trials and geometrical constructions. I also suggest that Marci's unusual coupling of chymical philosophy with mathematics was a move unusual in the history of alchemy; and that his chymical understanding of light belongs to an underexplored tradition in the history of optics, which is distinct from mechanistic and Aristotelian theories of light

The dissertation explores the intellectual and diplomatic life of an Imperial physician, Johannes Marcus Marci , and places his works within the broader cultural, intellectual, and socio-political context of Prague. Using Latin texts, dissertations, and letters of correspondence, I argue that alchemical philosophy constituted a prominent portion of seventeenth-century science. Marci's alchemical philosophy helped shape local debates about corpuscular matter theory, the physical nature of light, and theories of generation and decomposition, which were central to the development of early modern Bohemian natural philosophy. ;Part I sets forth Marci's biographical background and describes the role of imperial physicians in the Habsburg lands. In the second chapter, I investigate the environmental context of mining, which provided material incentives and court support for the study of alchemical procedures and theories about these material outcomes. ;Part II, examines how shifting political contexts complicated court patronage of alchemy. Marci was an imperial physician and Dean of Medicine in post-Rudolfine Prague, a period in which political circumstances, occasioned by the Thirty Years war, forced the merger of Prague's two university institutions, the Carolinum and the Clementinum. These institutional transformations compelled physicians to engage with new faculty and to re-evaluate interconnections between alchemical and scholastic philosophy. In Chapter II, I explore Marci's controversial matter theory in which he redefined ontological interactions between matter and "substantial form" by supplanting neoaristotelian substantial forms with his theory of seminal forces . ;In Part III, I look at the relations between mathematical sciences and alchemy through Marci's Thaumantias, in which alchemical philosophy informed his optics; and his Philosophia Vetus Restituta , where his study of light informed his alchemical philosophy. Chapter III discusses Marci's use of Kepler's concept of the vis motrix as the model for his seminal agents that directed generation in plants, animals, and humans. Chapter IV explores how Marci's alchemical philosophy informed his optical thesis that light is composed of differently colored rays that can be separated with a prism. ;The final chapter investigates an alchemical debate in which imperial physicians resolved a scientific puzzle and served a diplomatic role by quelling a potentially destabilizing social disturbance