Plant alchemy, Paracelsianism and internal signature theory in the writings of Guy de La Brosse (1586–1641)

In France, the Jardin des Plantes is one of the oldest surviving scientific institutions, the chief botanical garden and the host of many schools and centres studying the natural sciences. It was established in 1640 as the Royal Garden through the tireless labour of the physician Guy de La Brosse (1586–1641). The present article focuses on La Brosse's views of advancement of plant alchemy as the source of knowledge of plants. It discusses his adoption of the Paracelsian physician Joseph Du Chesne's (Quercetanus, 1546–1609) distinction between external and internal signature theory, opting firmly for the latter as the basis of true knowledge. The internal character, La Brosse argues, can only be revealed empirically, by fire analysis and the practice of distillation, which can also harness the occult properties of plants for human benefit.