The title is a bit over dramatic but, per the title, if you could contribute with one piece of knowledge to a book that every single individual should learn from in order to kickstart a civilization, what would be yours?
My personal choice would be the process of soap making, from scratch.
They’re soups but I have only ever seen them as condensed canned soups. They’re one of those ingredients I’ve used plenty of times but couldn’t really tell you much more about them.
So, its just chicken and mushroom soup. I was picturing specially flavoured cream (as in whisking cream).