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.
What is and how to fight for Democracy.
Considering no one has truly figured out how to make a Democracy survive, I’m impressed this is your contribution. You should probably be writing books before this one, if you have answers.