The Doctrine of Signatures in Early Modern Medical Practice

A walnut looks like the brain, so it can heal brain problems. In the early modern era, it was a popular belief that a plant's morphological resemblance to a human body part indicated its curative effect. Inherited from ancient authors, this idea was first conceptualised as the "doctrine of signatures" by German Paracelsian physicians. My doctoral research will examine how the doctrine of signatures was applied, developed and transformed in early modern medicinal practice. Through printed treatises, prescriptions and recipes, I will study how chymists brought out the effect of signatures through boiling and distilling, how female practitioners developed this doctrine in the kitchen, and how remedies based on this doctrine became popular in royal courts. My dissertation thus explains how early modern practitioners worked with complex theories, shedding new light on the relationship between learning and making, and theory and practice.