Thursday, October 4, 1582, went to bed as normal. The next morning, by papal decree, it was Friday, October 15. Pope Gregory XIII had just deleted ten days from the lives of everyone in the lands that adopted his new calendar, not through war or plague but with a stroke of the pen.
The old Julian calendar, running since Julius Caesar set it up in 45 BCE, drifted by about a day every century, slowly dragging the spring equinox out of place. Gregory’s fix was elegant on paper and bewildering in practice: landlords demanded a full month’s rent for a fortnight no one had lived through, wages fell short, and in some towns crowds accused the Church of stealing their days outright. The new rule that century years are only leap years if divisible by 400 quietly corrected the error for good, and the dates we live by today are still Gregory’s.
