This Sunday, we will all dutifully set our clocks back one hour for daylight saving time. But why is our day divided into 24 hours, each hour divided into 60 minutes, and each minute into 60 seconds?

A mysterious 5,000-year-old decision led directly to how we still count time today. In October 1793, the newly established French Republic embarked on an ill-fated experiment. It decided to change ...