German chemist who worked to reform medieval medicine. Philipus Theophrastus Aureolus Bombastus von Hohenheim, better known as Paracelsus, had trained as a physician and surgeon and held degrees from several universities in Italy. He theorized that illness was not caused by an imbalance in an internal system of humors, as medieval practitioners believed but was due to outside forces. He believed that the way to attack these invading forces within the body was through the use of chemicals rather than herbs or techniques such as bleeding. Paracelsus planned to create these chemical cures using the techniques of alchemy. Previously, the major goal of alchemists had been to find a way to produce gold from base metals; Paracelsus changed that to the production of medicines, setting the basis for modern chemistry.
Paracelsus was, by all accounts, a difficult man to associate with, having little tolerance for human frailties or for disagreement with his own ideas, roundly condemning practitioners of traditional medicine for their failure to adopt his ideas. Perhaps because of this, he failed throughout his life to find a permanent job or a university position. He died without ever seeing his ideas win favor among the medical and academic establishments. Although his work was instrumental in establishing the tenets of modern medicine, Paracelsus was not himself a scientist. He attacked the theory of humors on mystical, religious grounds rather than on scientific grounds.