ABSTRACT
Theophrastus Bombastus von Hohenheim, better known in history as Paracelsus, who was born in the Swiss village of Einsiedeln in 1493 and died in 1541, taught us that the severity of a poison was related to the dose (see Strathern, 2000). His citation “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy” is found in the first chapter of almost all textbooks of toxicology or pharmacology. However, the molecular theory was formulated more than 300 years later, and the law of mass action not until after the middle of the 19th century. Real rational toxicology and pharmacology are dependent on these laws, and hence could not develop properly before they were known.
