Why Do We Have 'Weeks' on Our Calendar?

What were you doing last week?

Week.

Week.

Week?

Have you ever wondered why we have weeks?

Why count off seven days and then start counting again?

Well, in anticipation of the startling answer, here's some stuff you already know.

Day: The day is based on the earth's rotation on its axis. One cycle, one day.

Month: The month is associated with the lunar cycle, the complete cycle from one 'new moon' to the next, about 29.53 days. (Try putting that on the calendar....)

Seasons: The four seasons are based on specific transition days as the earth orbits the sun. 

• The first day of spring is called the vernal equinox, when day and night are equal in length during the period in which the days are getting longer. 
• The first day of summer is the longest day of the year. 
• The first day of fall is the autumnal equinox, when day and night are equal in length during the period in which days are getting shorter. 
• The first day of winder is the shortest day of the year.

Year: The year is based on the earth's orbit around the sun, 365 1/4 days, to be almost exact.

Calendars: Mankind has spent a great deal of time devising calendars to mark time and set future observances of special days (holidays, or holy days). It seems that people are almost obsessed with organizing a calendar that keeps months aligned with the seasons. The trouble is those pesky fractions that throw things off: A month is not exactly 29 days and a year is not exactly 365 days. Not only that, there's not an exact number of lunar cycles in a year. So, it is next to impossible to make the cycle of the calendar line up year after year. That's why we have leap years and months of varying numbers of days. (Now that's a tougher challenge than your usual 7th grade word problem on fractions.)

Without the adjustments, we would have fractions of days just hanging around somewhere in the space time continuum and then we would eventually have a year in which the longest day of the year was in the middle of January. Think about it: short sleeves on New Year's Eve and heavy coats on the 4th of July (or something like that). In any case, there's a whole lot of fraction finagling to get the calendar to work out the way it does.

And, by the way, our current calendar, the Gregorian calendar, is only one of many. Other calendars have been used in the past (Julian calendar, Mayan calendar) and some countries still have a traditional calendar (China) though most have adopted the Gregorian calendar.

Days, months, years.
Earth, moon, sun.

You noticed the glaring omission, right? 
The week.

Where does the 7-day week come in?
There is nothing on earth and nothing in the sky that suggests a 7-day cycle.

Some folks think it was the Babylonians who invented the week because they were fond of the number seven. That is rather speculative since their numbering system was based on the number 60. (It is probable that they gave us minutes and seconds by dividing the hour into 60 minutes and the minute into 60 seconds. These were based on their number system.)

So, is there a better explanation for the week?

Open the Bible to Genesis 2. God intentionally rested from his work of creation on the seventh day.

By the seventh day God completed His work which He had done, and He rested on the seventh day from all His work which He had done. Then God blessed the seventh day and sanctified it, because in it He rested from all His work which God had created and made. (Genesis 2:2-3)

Was God really tired? Did He need to rest?
I think it had more to do with God's care for mankind. Just look at the words of Jesus as He commented on the day of rest, the Sabbath:

The Sabbath was made for man, and not man for the Sabbath. (Mark 2:27)

Since the creation of the world God's intention has been for man to take a break from his work and rest. (The word 'Sabbath' actually means 'rest,' not seven.)

When you consider the biblical teaching about the Sabbath as a whole, it is clear that God wants man to rest on a regular basis and to think about Him. As a part of His creation sequence, He intentionally rested, and as a result, established a 7-day cycle called the week.

Have you ever noticed that cows never take a break from their task of eating grass. The neighbor's dog never takes a break from barking...all weekend long. Yes, it's true, animals sleep, some hibernate; some plants become dormant, but all living things continue tirelessly from day to day without stopping from their natural cycle. In great contrast, God actually gave mankind a gift so that he would not have to work endlessly. God gave man a 'sabbath' day, a day for rest and reflection on his Creator.

God invented the week; and that's why we have weeks on our calendar.