Homeopathy was invented by the German physician Samuel Hahnemann (1755-1843) in the late 18th and early 19th centuries. It was both refined and popularized by the American physician James Tyler Kent. Homeopathy is based on the theory that each naturally occurring element, plant, and mineral compound will, when ingested or applied, result in certain symptoms. Hahnemann believed that, by diluting these substances in a standardized manner, one could reach the true essence of that substance. Hahnemann described this process of dilution as "potentizing" (German: "potenziert") the substance. These dilute amounts could then be used to treat the very symptoms they were known to produce.