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.
All the physics and metallurgy things. I am also slowly acquiring skills in construction and farming.
Don’t forget beer making! I understand enough about distillation to probably make liquor without killing people.
You don’t need distillation to make beer though, do you?
Nope. Just fermentation.
Sorry that was unclear. I can make beer and I bet I can make liquor too.