If I knew the answer to that, I wouldn't need a savior. It is clear in the word that the day of rest is not a trivial matter, and that disregard of the rest brings on hardship and disease.
"It is clear in the word that the day of rest is not a trivial matter, and that disregard of the rest brings on hardship and disease."
I do not doubt that rest is necessary.
My point was only that the 7 day calendar is quite unlike the year and the month. Everyone in the world came up with a 12 month calendar, because there are 12 moons in a year. And the cycling of the seasons and change of position of the stars on a yearly basis was known to all civilizations the world over.
But the seven-day week is not a natural cycle at all. It is not something that arose naturally everywhere, but came out of the Middle East only. The Jews believe that it was divinely inspired and told to them by God, and that may very well be true. The Almighty has His own purposes.
My only point was that the 7 day cycle is neither lunar or celestial. Indeed, there is no natural seven day cycle, no "natural week". It's a man-made thing, the week. That man made it under the inspiration of God is the Jewish assertion, and I think that's probably truly how it came about.