It’s Friday.
This means a lot to you.
It’s significant.
Your life revolves around Friday. And Saturday. And Sunday. And all the other days of the week.
They’re the framework for everything you do.
They dictate when you go to work, or when you go to school, or what days work is busy, or what days just kind of stink.
But seven seems like kind of an arbitrary number for how long a week is, right? Someone decided it would be seven, and by this point, we’re powerless to change that.
So how’d we get to this point?
Well, sounds like it, like most of Western law, can be traced back to the early days of Judaism.
According to our beloved Wikipedia:
A continuous seven-day cycle that runs throughout history paying no attention whatsoever to the phases of the moon was first practiced in Judaism, dated to the 6th century BC at the latest.
There are a couple theories for how it started. One relates to using the moon’s phases to measure months: Because the moon’s phases last about 29 and a half days, seven is closer to a quarter of it than eight. Evidently the Babylonians used a system with seven-day weeks and “intercalary” days inserted in between weeks and months to keep everything lined up with the moon and the sun. All of which sounds like a lot of work, but at least makes sense, and shows how day and night and lunar and solar phases—the things our ancestors all would use to measure time—don’t synchronize well at all.
So, the theory there goes that the Hebrews took it from the Babylonians.
But others theorize that the seven-day week actually revolves around the role of the Sabbath in the creation story, back in Genesis. On the seventh day, God rested, so on the seventh day, the Hebrews rested, so a seven-day week made sense.
Either way, the Hebrew people are the first known example of a society using the seven-day week with no adjustment to synchronize with the moon.
But it’s unclear whether they actually started it, or if the Babylonians were responsible for it spreading, or if everyone just kind of landed on that through some inherent piece of our brains that evolved to prefer seven-day weeks over the alternatives. It’s possible there’s just no way to know.
Other societies kept their calendars differently, but seven-day weeks were evidently present in a whole bunch of them. Not all of them—Rome used an eight-day week of sorts that didn’t fully fall out of favor until the fourth century AD. But enough of them for it to survive until today. Although, I mean, maybe there are societies out there we just don’t interact with a lot using eight-day weeks or nine-day weeks or no weeks at all. Who knows, really.
Anyway, either I’m doing poorly on Wikipedia today, or Wikipedia doesn’t have the answers to our question, because seven days still feels pretty arbitrary.
Happy Friday.
Wikipedia articles enlisted in this search for knowledge:
