The proposed Science and Society Dissertation Improvement Grant in the history and philosophy of science will support data collection at select archives in the U.S., Italy, and Great Britain in order to understand the creation, propagation, and changing nature of the works on poison, which quickly became a coherent genre in its own right over the fourteenth century. Its central questions are: Why was a philosophical treatment of poison suddenly important to physicians and their patrons? Why did lists of remedies for various poisons apparently become inadequate? How did definitions and understandings of poison change as works on the topic moved from lists of remedies to discussions of the nature of poison to discussions of physical interactions between poison and the body? These questions, though they can be answered through an investigation of poison literature, tell us much more about the interface between natural philosophy and medicine and how social contexts influence intellectual development and circulation of knowledge. The project serves as a litmus test for a constellation of related issues. It will first describe medieval poison literature, outline the philosophical debates regarding the nature, definition and operation of poison. It will explore the diffusion of a particular work across the European intellectual community, as well as provide a new avenue of inquiry into political influence on medicine at a time when the threat of political poisoning loomed large. Lastly, it crosses over a number of periodization boundaries, such as manuscript and print, and medieval, Renaissance, and early modern.