History
Roman history notes that the women washing in the water below the temples after sacrifices found the water there to be foamy and excellent for washing clothes. The fat had run down through the ashes and rain had washed it down the hill. They took credit for the invention of soap, although some historians believe it was actually first invented in Egypt. The Spaniards later found that they didn’t have to use animal fat; they used olive oil and created the gentle Castille soap.
In the United States, at the end of the 19th century, the meat packers discovered that they could take the fat from the pigs, make soap, and extract the glycerin for nitro glycerin. The money was in the glycerin, but with mass production and clever advertising the soap sold well too.
Justification
There are lots of reasons not to make soap at home. It takes a lot of equipment you shouldn’t use for other purposes. It is inherently dangerous and the raw materials must be respected. It takes some training and skill to make a product that is gentle and pleasant to use. But any soapmaker will tell you that the process is creative and addictive. The soap forms as if by magic. The fragrance of drying soap is intoxicating. The soap itself is better for the skin than commercially produced soaps.