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.
This exercise recurs regularly and there have been a few formulations.
One of the big ones is atomic theory. It took a long time to figure out - and I’m intentionally discounting the Greek version and monads here because I’m talking about actual atomic theory and not a philosophy of essences.
Darwinian evolution and Mendelian genetics are a second option, especially if you could squeeze in things like the germ theory of disease.
I’m not familiar enough with pure math to say that there’s one concept that would have let the Greeks or Mesopotamians develop the calculus millennia earlier than we did, but that would also massively accelerate scientific progress.
Not sure about the Greeks or Mesopotamians, but the concept of not burning down libraries might’ve helped the Romans 😂
“Romans go home!”
“Romanes eunt domus? People called Romanes they go the house?”