The Seven Days of the Week
Why Does a Week Have 7 Days?
Have you ever stopped to wonder why there are seven days in a week? Seven isn't a particularly intuitive number. It's a prime, so can't be divided down, and doesn't even divide cleanly into 365. Whereas there are possible mathematical explanations for the 24 hour day, the use of seven for the days of the week seems unjustified.So, why seven?
Some people simply like to point to the Christian Bible: it says that a week has seven days, therefore it does. Personally I find that answer unsatisfying (although it is interesting to note that there are also seven deadly sins - one for each day!).
The number seven has had mystical connotations in many ancient societies. We know that the ancient Babylonians used a seven day week. This brings us to what seems to be the most likely reason for the origin of the seven day week:
Astronomy & Astrology
The ancient Babylonian calendar had seven days in a week, each dedicated to a deity of one of the seven "luminaries" seen in the sky.Seven? But there are (at least) nine planets!
True, however before the invention of modern powerful
telescopes only five could be seen in the sky.
It's five now? So where do we get seven from?
Ah, because the ancient civilisations included the Sun
and the Moon with the planets. So we have 5 + 2 = 7
Each of these luminaries was usually associated with a god. Although the names of the gods changed over the centuries, their origins often remained clear.
This connection between the days of the week and the visible luminaries - which form the basis for much astrology - is continued in the English and French names for our modern week:
| Monday | Lundi | Moon | ||
| Tuesday | Mardi | Mars | ||
| Wednesday | Mercredi | Mercury | ||
| Thursday | Jeudi | Jupiter | ||
| Friday | Vendredi | Venus | ||
| Saturday | Samedi | Saturn | ||
| Sunday | Dimanche | Sunday |
There are other connections that can be made between the English day names and the Norse pantheon: Wednesday - Wodin, Thursday - Thor, Friday - Freya.
The atronomical basis for the seven days of the week isn't the only theory, other suggestions have been made.
Some people think that it might simply be a simplification of a quarter month. A lunar month is approximately 28 days and many pagan societies used a lunar calendar, so a quarter month would have been a useful measurement.
Of course there is no reason why both of these theories - and more - should not have contributed together to the adoption of our modern seven day week.