The Sumerian calendar

The Sumerian calendar

The Sumerians and later the Babylonians were the first known civilizations to use what we now recognize as a lunisolar calendar.

By the 21st century B.C. the Sumerians had come up with a solar year consisting of 360 days. It was made up of 12 lunar cycles (354 days) which were rounded up to 360, forming 12 months at 30 days. What differentiated the Sumerian calendar system from any other lunar calendars of this time, was the way they measured time. The Sumerian calculations are all heavily based on the numbers 6, 12 and 60, still used today.  Our current year has 12 months and the day in many countries is structured as 12 hours am and 12 hours pm. The hour itself has 60 minutes and every minute has 60 seconds.

To bring the shortfall of these embellished lunar months into sync with the solar year, the equinoxes (where day equals night) and the solstices (longest and shortest day of the year), the Sumerian astronomers introduced an extra month every four years. This is what we now call a leap year.

The Sumerians also recorded ‘day qualities’. Enuma Anu Enlil is a collection of stone tables and oracles compiled by Sumerian and Assyrian scribes.  The tables include information about lunar eclipses, weather events, the movement of the stars, planets and constellations. The most important part was the interpretations of all these cosmic movements and what they meant for life on earth. The dominant observations concerned the moon cycle and its relation to the other stars and the sun.

 It is still unclear where all this knowledge came from. But what is certain that it helped to shape the later famous Babylonian calendar. Although these were humble beginnings, these scribes crucially laid down the foundation of the houses, the star signs and the creation of the zodiac (called the ‘circle of the animals). They named many star constellations in the sky and created the basic principals of Western astrology. The movements of the planets and stars were meticulously observed, recorded, and interconnected with symbolic meaning. These observations traveled to other countries, particularly to India in the 3rd century B.C.

From 499.B.C. the Sumerian calendar transformed into a proper lunisolar calendar. The shift came when it was recognized that 19 solar years equal exactly 235 lunations (moon cycles) and this formed the first proper re-occurring connection between the solar and the lunar cycle.  This principle was formally described by the Greek astronomer Methon of Athens in 432 B.C. when he ‘discovered’ the Metonic cycle. But most probably he came across the Babylonian calendar and recalculated their calendar formula.

The Sumerian calendar month started at sunset with the first sighting of the new crescent moon (Waxing Moon) and ended with the last sighting of the descending crescent (Waning Moon). Once the Waning moon had vanished there followed a period of the ‘disappeared moon’ (New Moon) when no moon was visible in the sky.

This played a big part when planning to travel, especially crossing a desert. Due to the hot climate caravans preferred to travel at night. But with no moonlight to guide them, there was a great chance of getting lost.  Therefore the New Moon became known as the time to stay at home and rest.  A concept we still use in the LWTM life goal planner.

On the other hand, the moon’s opposite position in the lunar cycle – the Full Moon-  was the time for gatherings and ceremonies. Then people could easily find their way home once it got dark.

The roots of the Sumerian lunisolar calendar still exist today, particularly in many religious calendar systems and associated practices.

The ‘Living With the Moon lifestyle calendar’ is also based on the Ancient Lunisolar Calendar. It is now believed that this calendar model was in far more widespread use than initially thought. For example, many believe that the Minoan civilization (3000-1450 B.C). followed this calendar system. 



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The origin of the moon calendar

The origin of the moon calendar

People have looked up into the sky for thousands of years to find purpose and a sense of time and order. In doing so pre-historic societies chose the path of the moon as their first cosmic guide.  Marked animal bones, recently discovered in the Dordogne region in France date back to 28,000 B.C. They show a pattern of 7 or 13 notches and are believed to be very first calendars known to man.

It is hardly surprising that early man chose the path of the moon. Firstly it is the most visible object in the sky and in the absence of electricity was the only viable light at night (bar fire). The path of the moon is also inextricably connected to the tides and the human fertility cycle. In fact, the moon had always been connected to fertility, rainfall, birth and death.   

Counting the nights from no moon (New Moon) to Full Moon and back again are roughly 28 days. The Waxing (growing) and the Waning (descending) phase were further subdivided into 4 quarters and served as the blueprint of our week.  (28:4=7). 

The word ‘calendar’ derives from the Latin word ‘calendarium’, which means register and structure. So having a calendar was a big leap forward. Now it was possible to structure festivals, daily routines and agricultural events – and they could be planned in advance. This was particularly important when humans started to settle down and then getting together for celebrations/market day and other social events really took off. It was of course the calendar, the common structure for measuring everybody’s time, that made these events possible. Apart from timing celebrations it also enabled dates for planting, harvesting and collecting taxes. 

The Ancient Greek, Roman and Chinese year consisted of 12 moon cycles (354 days) and occasionally a 13th cycle was included to keep the Ancient Lunar year in sync with the seasons. Many religious calendars operated (and still do) in sync with this lunar calendar model. Others morphed into a lunisolar calendar model. 

The number 13 became the ‘pagan number’, the unlucky number and the number of the ‘dark side’. Just think of Friday the 13th as THE unlucky day. Friday was the day of the of the goddess Venus, the day of love and fertility and 13 after the 13th lunar calendar month 

In Sleeping Beauty 12 witches were invited, but the 13th, the bad witch, had to stay outside.  Can you see the connection?

The sun, the dominant male force with its 12-month solar calendar = good.
The moon, the subservient female force with its 13-month lunar calendars = bad

The Greeks and early Romans lived their lives solely by following a lunar calendar, first mentioned in the 13th century B.C. It was not only the time structure that became so useful. They concluded that the moon with its varying influence affected the tides, crops and even human behaviour. They recorded these observations and inserted these meanings into their calendar. This would later inform the ‘varying day qualities’. This Ancient Lunar calendar model was passed down from one generation to the next, each adding new observations and discoveries. 

One example of these lunar calendar guides is depicted in the poem ‘Work and Day’, written by the Ancient Greek poet Hesiod around 800 B.C. It depicts rural scenes from Ancient Greek life, mixed with moral hints and practical tips. 

“Avoid the thirteenth of the waxing month for sowing, it is best for setting plants. And in the waning month, on the fourth, beware of heart-consuming worries…”

Four hundred years later Hippocrates connected the lunar path to the successful outcome of medical treatments and diseases such as epilepsy.

The Sumerian and later the Babylonians developed a sophisticated calendar that took the path of the sun as well as the lunar cycle into account. They created the first ‘Lunisolar calendar’. 

The Babylonians were keen astronomers and astrologers and they also established the notion that days have energies/forces and they called them ‘ Individual Day Qualities’. The “Living With The Moon’ life-style calendar is a modern reincarnation of the Ancient Babylonian calendar model.

Nowadays most of the world has adopted the Gregorian calendar model, based on the Ancient Egyptian calendar which only follows the path of the sun and treats every day the same, no changes of day qualities.

Although the solar calendar was first established around 4200 B.C. it took a long time for the rest of the world to change over. In fact, Russia only adopted the Gregorian calendar model in 1919 (the year the Communist Party came to power in Russia)  and China adopted the solar calendar in 1949 (again the year of the Communist revolution).

But the traditional Chinese New Year is still calculated in accordance with the moon cycle and its starting date is not static but varies year on year. As does Easter and Ramadan.

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