The engine of this revolution was Theophrastus Bombastus von Hohenheim, a Swiss physician who took the name of Paracelsus (1493-1541), by which he became well-known in history. He chose this name to affirm his superiority over Celsus, Roman encyclopedist whose work De Medicina (On Medicine) had been republished in Europe in 1478.
 

Paracelsus flatly condemned the medicine of the time, questioning everything, even the four elements of Aristotle. In his work, Paracelsus named three immaterial principles of the human body: combustibility, or the sulfur principle; liquidity and volatility, or the mercury principle; stability and solidity, or the salt principle. The humoral galenic pathology was thus rejected and replaced by the new theory of disease and pharmacotherapy developed by the Paracelsians.

This new theory – iatrochemistry – argued that disease was an anomaly and not an imbalance of humours. This anomaly was a natural manifestation, hence chemical, and thus would have to be chemically treated. The human body was considered a laboratory and its chemical processes depended on a vital force – the archaeus. The disease meant that the archaeus was in a morbid and sickly state that occurred when the chemistry of the body was disturbed; this state could be remedied using chemical medicine.

Consequently, dyes, extracts and essences had a very important role in Paracelsus’ drug therapy. Essential for the preparation of medicines in this period was the art of alchemy. Paracelsus developed distillation techniques that were appropriate for volatile substances, and thus the use of various types of alcohol, spirits, essences and oils increased considerably. Strong mineral acids, including sulfuric acid and nitric acid, were also discovered. Finally, advances in metallurgy allowed the existence of provisions of mercury, antimony, lead, and also of arsenic, iron, gold, copper, cobalt, bismuth and zinc. From these new compounds were produced, such as the corrosive sublimate of mercury and calomel.

The 17th century pharmacist thus became a chemist (and also a botanist) and the pharmaceutical workshop became a chemical laboratory where distillation, evaporation, incineration, sublimation and leaching processes were put into practice.

After the discovery of the new worlds, the compilation and description of the new medicinal plants, such as guaiac, Tolu balsam, Peruvian balsam, salsaparilla, jalapa, rhubarb, capivi, chinchona and sassafras, was made. But the greatest discovery was cinchona, discovered by the Jesuits in Peru in the 17th century. They were responsible for recognizing its properties in the fight against malaria. Also, tea, coffee, chocolate and tobacco became commonplace in European habits.