[Russell Cissell]

I will add a bit of trivia. . .

People living along the Nile River thousands of years ago accidentally discovered "soap" when washing their clothes in the river. They found that when they washed their clothes in certain spots along the bank the clothing would get much more clean.

Turns out these spots were all just down stream from where they would cremate their dead. As the bodies burned, their fat was rendered and dripped into the ground. As the lipids in their fat leeched their way through the soil to the river they would pass through naturally occurring lye in the soil.

The combination of this fat and lye would create naturally "soapy" water for them to wash their clothes in. Back in the day, I suppose they credited the Gods for this. Today it is seen as just a bit of coincidental chemistry.