“Seven days,” wrote Witold Rybczynski in the August 1991 issue of The Atlantic, “is not natural because no natural phenomenon occurs every seven days.” The year marks one revolution of the Earth around the sun. Months, supposedly, mark the time between full moons. The seven-day week, however, is completely man-made.
If it’s man-made, can’t man unmake it? For all the talk of how freeing it’d be to shave a day or two off the five-day workweek, little attention has been paid to where the weekly calendar came from. Understanding the sometimes arbitrary origins of the modern workweek might inform the movement to shorten it.
The roots of the seven-day week can be traced back about 4,000 years, to Babylon. The Babylonians believed there were seven planets in the solar system, and the number seven held such power to them that they planned their days around it. Their seven-day, planetary week spread to Egypt, Greece, and eventually to Rome, where it turns out the Jewish people had their own version of a seven-day week. (The reason for this is unclear, but some have speculated that the Jews adopted this after their exile in Babylon in the sixth century B.C.) At the very latest, the seven-day week was firmly entrenched in the Western calendar about 250 years before Christ was born.