Times of Day

Why did humans need fixed times of the day, like "noon" and "midnight"? 

I was wondering about these terms and writing a post for my origins blog, and came across additional information beyond etymologies that I'll post here.

There are several answers to why humans needed fixed times of the day. We love to organize things, and communal life included religious rituals, markets, work schedules, and meetings, and those needed a shared system of timekeeping. 

Times of day allowed long-distance coordination as societies expanded and trade increased, people needed consistent points of reference—even if the Sun wasn’t visible.

Things like contracts, taxes, leases, transportation, and recordkeeping all require clear definitions of when one day ends and another begins. 

These official - and eventually precise - times of day enabled scientific and navigational progress since astronomy, calendars, and navigation at sea relied heavily on precise solar measurements—especially noon.

fixed times of day like noon and midnight to organize life around the natural rhythms of light, darkness, and the movement of the Sun. These terms didn’t appear all at once—they evolved over thousands of years as people developed more precise ways to measure time. 

Noon originally meant the moment when the Sun reached its highest point in the sky. This is now called "solar noon." This was a natural reference point for early societies: The Sun’s highest point was a dependable daily marker. It divided the daylight into “before” and “after.” Farmers, travelers, priests, and traders could all use it to coordinate activities. 

In ancient civilizations — Egypt, Mesopotamia, Greece, and Rome — solar noon was the anchor for their earliest "clocks" (like sundials). Even when mechanical clocks arrived in the Middle Ages, they were adjusted every so often to match the actual solar noon. 

 The word shifted over time: In medieval Latin and Old English, nona meant the ninth hour after sunrise (about 3 p.m.). Over centuries, the prayer schedules of monks shifted, and by the 14th–15th century, English speakers were using noon to mean 12:00.

Midnight is the natural opposite of noon, and after noon was defined as the midpoint of the daylight period; it made sense to divide the entire 24-hour cycle into two halves. Midnight became the point exactly opposite solar noon. A convenient boundary between one day and the next, and it was a reference point for the start of calendars, laws, and later, timetables. 

Before mechanical clocks, people didn’t think much about precise (hours and minutes), and night was divided into “watches,” or segments, mainly for keeping guard. Mechanical clocks (1300s onward) made a precise 12:00 a.m. possible. When time zones were standardized in the 19th century for railroads, midnight officially became the start of the civil day.