[First posted on The Times of Israel: http://blogs.timesofisrael.com/beshalach-why-seven-days/]
Ibn Ezra Exodus: Beshalach
Why Seven Days?
“Time is the most valuable coin in your life. You and you alone will determine how that coin will be spent. Be careful that you don’t let other people spend it for you.” -John Dryden
A seven-day week does not reflect any natural phenomena. As opposed to a day, a lunar month or a solar year, a week is an artificial creation.
Some interesting exceptions to the seven-day week include the Igbo people of Nigeria (4 days), the Javanese of Indonesia (5 days) and the Akans of West Africa (6 days that have been mixed with a 7-day week giving a 42-day cycle).
Historically, the Romans had an 8-day week for a time, until they met the 7-day week which became more popular. Both ancient China and Egypt had a 10-day week. In more modern times, during the excitement of revolution, the French adopted a 10-day week. It lasted for nine and a half years (1793-1802). The Soviets experimented with a 5-day week from 1929-31 and then tried a 6-day week until 1940. None of these counting systems have survived.
Why does almost all of humanity follow a 7-day week? Ibn Ezra claims (Exodus 16:1) that it comes from the Torah. God mandated a 7-day week to remember Creation as well as to remember the Exodus. Curious how the entire world has adopted this Jewish tradition – in most cases without even knowing it.
I wonder what other traditions have permeated the world and which others may still do so?
To Jared Diamond and his glorious book Guns, Germs and Steel, where among other things he highlights potential causes as to the fate of societies and civilization.