The science of soap is more complex than one might imagine, requiring at least a rudimentary knowledge of chemistry. Even the most basic ingredients of soap rely on key reactions with other ingredients — a give and take that makes you wonder how we ever figured out soap in the first place. It makes some sense then, that the creation of cleansing products was supposedly discovered by accident.
Historians believe that the word “soap” is derived from the ancient Roman temple site at Mount Sapo, a spot used for the regular ritualistic sacrifice of animals. Animal fat would then run down the mountain into the nearby Tiber River, combining with fire ash to form a substance that women, innocently washing their clothes on the river’s banks, found particularly handy.