“One of the cornerstones of human life is that there are twelve months in a year. Recent archaeological discoveries suggest that we have been notching off the days of the cycle of the moon for hundreds of thousands of years, using stone tools to mark bone. And it must have been one of our first pieces of inherited science that the counting off of twelve moons fitted magically into the annual miracle of the changing seasons. As there are (very nearly) thirty days in each lunar month, one of the very first joys of multiplication must have been that when multiplying these twelve months by thirty, you create 360, which is (roughly) how many days there are in the year. So we have always divided up the heavens—and any circles we come across—into 360 degrees.
The added harmony of the tides, and the female cycle of fertility fitting into the lunar months, provided further proof that there was a pattern and an order to the world. And one of those patterns was very clearly that twelve moons make one year. This innate power of twelve was further reinforced when the heavens, through which the sun was imagined to process, were also neatly divided into twelve segments. Each of the twelve signs of the Zodiac were allotted 30 degrees of the Heavenly circle very early on in mankind’s construction of an ordered world. This would later be reinforced by other twelvefold divisions, aspiring to create the same graceful, ordered inevitability.
These twelvefold divisions of the night sky and the moon also made for very easy organization. A clan or a district could become associated with a particular month, and so, whether it was taking turns to guard a citadel, provide food for a shrine or furnish a choir for the temple at the next full moon, it became almost a natural habit of mankind to form themselves into twelve.”
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.