Gradus Dimetiri: intensity and classification of complexions in 14th-century Italian medicine

This paper focuses on the scholastic approach to the intensity of complexions and presents some evidence as to how the meaning of complexio evolved in fourteenth-century Italian medicine: namely, how it was conceptualized, visualized, and finally quantified. In the first part, I summarize the philosophical development of complexio, pointing out how the concept differs from simple mixtures, thereby allowing for the mathematisation of compounds and their intensity. I then move on to consider the links between medicine and mathematics and present the schemes provided by Gentile Gentili da Foligno (1280/90 - 1348) as a case study, analysing their philosophical premises and implications for medical treatment more generally. In the final part, I argue that, quite aside from representing early forms of the mathematisation of qualities, schemata and diagrams also captured the medieval ideal of the cosmos, a hierarchical progression of forms ordered in ascending degrees of perfection and nobility.