Paracelsus introduced several lasting medical innovations: chemical urinalysis, a biochemical theory of digestion, wound antisepsis, the use of laudanum for pain, and the use of mercury for syphilis. His books were mainly about human nature and the place of man in the cosmos, but he also wrote important treatises on syphilis.

The Latin motto of alchemy was solve et coagula, which means “separate and combine.” Alchemy was practiced throughout the Christian, Islamic, and Jewish world until the nineteenth century and beyond. Traditionally, the central project of practicing alchemists was to discover how to turn base metals into gold. Second to this was a search for the elixir of life, which would cure all sickness and enable immortality. Medieval alchemists sought a philosopher’s stone, which they believed would make both tasks possible, and they also worked on formulas for a universal solvent or aqua vitae. One form of aqua vitae has endured as a concentrated ethanol liquid: ethyl alcohol.