The Seven Wanderers

There is no reason a week should be seven days. The day is one spin of the Earth; the year, one lap of the Sun; the month roughly follows the Moon. The week answers to nothing in the sky — yet it rules your life, splits your work from your rest, and runs in near-perfect step across almost the whole planet. You inherited it from sky-watchers who died thousands of years ago.

The Babylonians, watching the heavens with patient obsession, counted seven lights that wandered against the fixed stars: the Sun, the Moon, and the five planets the eye can catch. Seven felt complete, sacred. They gave each wanderer a day, and the rhythm held — handed to the Greeks and Romans, who named the days for their gods, then carried by empire and faith around the world. The old gods are still in the names: Saturn's day, the Sun's day, the Moon's day.

Nothing in nature forces the world to keep this beat. But it does, in unison, because a few star-watchers in ancient Mesopotamia found seven lights beautiful — and the habit never broke.

You will rest this weekend on the authority of dead Babylonian astrologers.

And if the shape of your week is an ancient accident — what else in your day is a fossil you've never noticed?