"Summus atque felicissimus salium": The Medical Relevance of the Liquor alkahest

This paper analyzes the development of the concept of alkahest from its origins in the Paracelsian corpus to its mature form in the works of Joan Baptista van Helmont (1579-1644) and his successors. Historians of science have usually focused on the chemical aspects of the alkahest, taking into account especially the claims that it was a substance capable of dissolving all kinds of matter. This paper shows the medical implications of the alkahest: it was not only a "solvent," but an important means of revealing nature's secrets and of producing medicines. The properties ascribed to the alkahest fit perfectly within Helmontian theories about matter, disease, and cure.