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Have you ever wonder why you start a new week every 7 days? Unlike months, tied to the moon, or years, bound to Earth’s orbit around the sun, the week has no obvious anchor in nature. Yet, across much of the world, we live our lives by this arbitrary-seeming cycle, resting on the seventh day, dreading Mondays, and celebrating weekends.
The seven-day week began in ancient Mesopotamia. Babylonians, who excelled at astronomy, divided the heavens according to the seven celestial bodies visible to the naked eye: the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Meanwhile, Hebrew tradition codified the idea in scripture as the story of Creation and the Sabbath reinforcing a divine seven-day pattern. This concept traveled with Jewish communities and their texts, embedding itself deeply into Western and Middle Eastern cultures.
Rome at first resisted. Their calendars used eight-day market weeks, more practical for commerce than cosmology. But as the empire absorbed eastern religions and ideas, the seven-day rhythm spread. By the time Emperor Constantine made Christianity the empire’s favored faith in the 4th century CE, the seven-day week had triumphed. From there, it spread across Europe, then outward through colonization and globalization, quietly becoming the world’s default unit of lived time.
Any attempts to change this accidental pattern, such when France tried a 10 day week during French Revolution, seem destined to fail. Today, our phones, work schedules, and vacations all run on this ancient template. The seven-day week is less a law of physics than a spell of history, one that still governs how we measure the rise and fall of our lives.
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