Most units of time are based on nature. A day is one rotation of the Earth. A month is the moon's orbit. A year is the Earth's path around the sun.
But a week? There's no natural explanation for it. (See the video at the top of this article.)
That's why ancient cultures defined the week in vastly different ways: four days in West Africa, 10 in Egypt, 15 in China.
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In the 1930s, the Soviets tried to eliminate the seven-day week entirely - first replacing it with a four-day week, then a five, "to facilitate the struggle to eliminate religion."
They were at least right about the source. The seven-day week comes straight from the Bible.
In Exodus, God commands: "Six days you shall work, and on the seventh you shall rest."
That short verse carries deep insight. First, it applies to everyone. Second, it treats work not as a necessity, but as a value.
The Torah doesn't say "work must be done," but that you shall work. The work itself matters regardless of the outcome.
This work doesn't need to be paid. Volunteering and child-rearing certainly count as long as the activity is demanding, consistent and productive.
The second insight can be seen in the life of Joseph, the only person in the Bible called a "success" - twice. This happened once as a slave, and once as a prisoner - and all the time with God by his side, whom he constantly cited (even as he, unlike his father Jacob and grandfather Abraham, never spoke with God).
Still, work must stop.
The seventh day, Shabbat, is not just a break. It's a weekly reset, a day to gather, reflect and reconnect.
The Jewish tradition calls it "a taste of Heaven on Earth."
Modern culture, though, swings between extremes.
For most of the 20th century, work was considered an unfortunate financial necessity to be escaped.
We see this in popular music, such as "Heigh Ho," "9 to 5" and "Taking Care of Business" - all songs about how work is meaningless drudgery.
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Popular commercials in the 1980s and '90s portrayed the ideal life as one of leisure: playing polo, loading fancy dogs into a car and diving off a yacht into the ocean.
Then, around the year 2000, everything flipped. Suddenly, busyness became the new badge of honor.
A new locution entered the lexicon - that people are "crazy busy."
This strange expression became so commonplace that it became the quintessential humblebrag.
It even took on a shortened version for those who were too busy to say the whole four syllables - that one's schedule is "crazy."
Neither extreme works. The leisure advocates need to understand what modern studies show time and again: Happiness at work is key to happiness in life.
This is partially because we spend much of our time at work, and it is hard to enjoy life if we dislike how we spend most of our work hours.
Contemporary research has shown that we can enjoy and find meaning in any job as long as we frame it correctly. This is called "job crafting."
A Wharton study found that hospital custodians who "job craft" and viewed their work as part of "healing patients" were more fulfilled and more successful than those who saw it as menial labor.
The biblical Joseph would have been proud.
But that's not the whole story.
Numerous studies have found that there is a productivity ceiling.
The first research on this topic was done by the British Ministry of Munitions, which established a committee in 1915 to assess the work that resulted in equipping the soldiers in the Great War. They concluded that the British war effort required giving workers a Sabbath - so that the workers would produce more.
The report, in part, said that "the evidence is conclusive that Sunday labor, by depriving the worker of his weekly rest, offers him no sufficient opportunity for recovering from fatigue … Seven days' labor only produces six days' output and … reductions in Sunday work have not involved any appreciable loss of output."
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A century later, John Pencavel, a professor at Stanford, analyzed the data using modern tools.
He determined that production correlated with work hours for the first 49 hours a week.
The rate of production slowed for the hours 50 to 55.
However, there was no increase in output from hours 56 to 70. The Economist, in reviewing Pencavel's work, concluded, "That extra 14 hours was a waste of time."
And so, we now have the number of what we have termed the "productivity ceiling": It's 55 hours a week.
And here's the amazing and maybe divine math.
A Sabbath observer can work 10 hours a day for five days a week.
He can really only work half a day on the sixth, as he needs to prepare for Shabbat - leaving him with a 55-hour work week.
So God was right.
The good life isn't all leisure or all work.
It's six days of meaningful work, followed by a seventh day of sacred rest.
Mark Gerson's new book is "God Was Right: How Modern Social Science Proves the Torah Is True," published by BenBella Books and distributed by Simon & Schuster (June 2025). This article is the second in a series featured exclusively by Fox News Digital.
