#1483 When did a week get 7 days?

When did a week get 7 days? People first used a 7-day week over 4,000 years ago in the Akkadian Empire.

When we think about it, there is no logical reason why a week should have seven days. You cannot divide the year up into 7s. For a while, the French tried a ten day week, but that didn’t work either. In fact, there is no number of days that you can equally divide the year up into, so any length of the week will always be arbitrary.

It is probably quite common to think that the 7-day week we have today came about because of the Bible. In Genesis, God created the heavens and the Earth in 6 days, and on the seventh day, he rested. However, the origin of the 7-day week predates Genesis and the Bible by at least a thousand years, possibly even two thousand. No one knows when Genesis was written. There are two theories. One is that it was amalgamated from various texts stretching back to the 9^th century BC. The other theory is that it was written after the 5^th century BC. Whichever theory is correct, the Bible was written over 1600 years after a 7-day week had first been used, so it is likely that they just used what was common at their time.

I say that the 7-day week was first used during the Akkadian Empire, but no one actually knows that. The first evidence of a 7-day week comes from this time, but it is hard to find evidence of something like this because even though writing existed, not many people could write and not many things were written down. Living in a heavily documented time, we forget that most things were not written down in times gone by. In roughly 2300 BC, king Sargon of Akkad decreed that the week should have seven days because seven was a very important number. There were seven celestial bodies visible to the naked eye. These were five of the planets, the sun, and the moon. He may not have been the first person to use 7 because the Babylonians and the Sumerians also used the number 7. It is very likely that they also had a seven day week because they celebrated phases of the new moon on every 7^th day. That doesn’t quite work because the phase of a new moon is seven days and nine hours, so it goes out of sync pretty quickly. To get around that, their last week of the month needed to be eight or nine days long. And many scholars think it is also quite likely that the Jewish idea for seven days and the idea for the creation story in Genesis came from the Babylonian creation myth called Enuma Elish.

Seven days in a week became standard in a lot of cultures, but not all. The Roman Empire used an eight day week called a nundinum, although it could technically be called a seven day week plus one. The eighth day of every week was a day off for many people. The Romans took this idea from the Etruscans, where a lot of Roman culture came from. The 8-day week survived in the Roman Empire until 321 AD when the emperor Constantine moved Rome over to a 7-day week to align with the Christian Bible. It wasn’t hard for him to do because the eighth day had been dying out ever since Julius Ceaser reformed the calendar, over 200 years before Constantine. Often, some people would follow a seven day week and some people an eight day week, which must have been fairly confusing. Constantine put the seven day week into law because it was pretty much the norm by then, and he designated the seventh day as a legal day of rest.

So, most of the developed world has a seven day week because of the Roman Empire and the Bible, which was spread around the world by European conquerors. The names of the seven days also came from Rome, at least for the majority of the countries whose languages are based on Latin. The days were named after the gods, who were named after the planets in turn. They named days after the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. You can still see this in languages like French and Spanish. Our weekday names in English came from mostly Norse gods or Germanic words, although we kept the days named after the Roman god Saturn (Saturday). Our days are Sunday, named after Sunna, Germanic for sun. Monday, named after Mani, Germanic for moon. Tuesday, named after Tyr, the Norse god, probably of war. Wednesday, named after Woden (Odin), the father of the gods. Thursday, named Thor, the Norse god of thunder. And Friday, named after Fria, the Norse goddess of marriage, prophecy, and motherhood. And this is what I learned today.

Sources

https://www.britannica.com/science/week

https://www.rmg.co.uk/stories/time/why-12-months-year-seven-days-week-or-60-minutes-hour

https://en.wikipedia.org/wiki/Week

https://en.wikipedia.org/wiki/Sargon_of_Akkad

https://www.almanac.com/why-week-has-seven-days