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 probably aren’t. But they are qualified to comment on a theoretical post about the subject.
OP is asking what each person would contribute, not that each person must contribute something that they are qualified to. Which, for the most of us, is nothing. So get off your “intellectual” high horse and contribute to the conversation or change your non-contributions to silence instead of pedantic bullcrap.
I guess I misunderstood the question as being what we we’re capable of personally contributing.
If it’s just hypotheticals, I would contribute antibiotics and how to make those.
I read it as “what do you have enough knowledge of that you could aid in the birth/advancement of a new civilization?” Doesn’t matter if you have it fully figured out, just what knowledge can you provide that would be highly valued if all knowledge were otherwise lost.