I mean, if today i.e. is Sunday then someone long time ago should have said “Today will be Sunday” for the first time in a period from today that is multiple of seven. I was assuming that it was Pope Gregory XIII in October 1582, but looks like he is not. I failed in googling and duckduckgoing out the answer, so I ask for Lemmy’s collective wisdom!
EDIT: so question is not about the origin of 7-day week and sequence of weekday names, but about the exact reference point (day) of today’s weekday countdown. From when have people stopped adding or ommiting any adjustment ‘out-of-week’ days (like in Babylon or Rome) and kept counting to seven till today? In other words, there should be a point exactly N x 7 days ago from which the 7-day countdown has not been interrupted. Or at least the earliest known day in history that everyone on Earth agreed upon as a reference point
Ok, let me rephrase your rephrase to be what question I think you’re trying to ask.
At some point we had decided on a seven day week with week names. That’s fine. But we must also have decided at some point that today was Wednesday in this system.
So I think you’re asking “what is the first day we all agree was definitely a Sunday, such that all Sundays after were based on that”. Or put another way, at what point did the days of the week get locked to the days of our year.
I don’t have that answer, but your question confused me, so I’ve reworded it.
Yeah, thanks, that’s pretty much it! Except we cannot really make days of the week get locked to the days of our year because 365 is not divisible by 7, and we’re adding 1 day to February every 4th year on top of that.