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.
Someone, a philosopher, did that. Minimalistic, factual, objective, and a complete failure.
We don’t get the language we want but what we need.
Removed by mod
A philopher from an eastern country, pre USSR. I can’t recall the name; was made aware of the person in a YT rabbit hole. That tidbit stayed but the name vanished.