1538

Toxicology

Paracelsus (1493–1541)

Swiss alchemist and natural philosopher Paracelsus spent his life practicing medicine, metallurgy, astrology, and whatever else the market would bear. He lived when alchemy was disappearing from the world and no one was quite sure what would replace it. The centuries-old quest to make gold and silver from base metals was, by that time, a long list of cold trails and dead ends. Paracelsus pointed the way forward when he said, “Many have said of Alchemy, that it is for the making of gold and silver. For me such is not the aim, but to consider only what virtue and power may lie in medicines.”

By all accounts, he was not an easy person to get along with, and he did not mellow with age (which probably helps account for the long list of destinations he turned up in during his forty-eight years). One part of his personality served him very well, though: he became well known as someone who refused to believe that something was true just because orthodoxy deemed it so. Unfortunately, he demonstrated this by publicly burning copies of ancient medical texts while he proclaimed his contempt for them.

Paracelsus is most remembered today for asserting that illness was often caused by outside agents. His studies of the (all too numerous) diseases of miners furnished him with plenty of prescient observations, such as the idea that slow-developing lung problems were caused by toxic vapors (rather than by evil mountain spirits bent on revenge, the more popular theory at the time). These gave force to his immortal adage “the dose makes the poison,” which appeared in his 1538 treatise Septem defensiones. Everything is toxic in a high enough dose, but some things never stop being toxic, even at miniscule doses.

This watercolor portrait of Paracelsus at age forty-seven is loosely based on a fifteenth-century engraving of the vitriolic toxicologist.