Moon Rhythms 1: Why is a Month?

I committed a small paperwork error a couple of months ago.  Having neither looked at a paper calendar nor run through that old rhyme (you know, “Thirty days hath September…”), I scheduled a trip into the woods for a day when I should have been filling out timesheets.  No big deal.  But it did spur the question of why the months vary when the original astronomical timer – the lunar cycle – does not.

I quickly realized that the history of calendars is a rabbit hole I don’t wish to go too far down.  A couple of links led me to more queries, and more links.  Just going to the Wikipedia article on calendars showed a slew of hyperlinks waiting to keep me up until dawn.  But I’m not writing a book on the subject, so if I can provide enough information to whet your thirst for knowledge, that will suffice.

The lunar month, when measured from new moon to new moon, is around 29.5 days long (there are at least 4 other ways to measure a lunar month, but I think this is probably the most relevant for most people).  The cycle of moon phases as it waxes and wanes in the sky is both consistent and spans a useful length of time, making the cycle a natural point of reference for measuring time.  Not surprisingly, the word for “moon” and “month” are closely related or even identical in a number of language groups; in English, “month” derives from Old English monað, which is cognate to mōna, “moon.”

A lunar-based calendar has the benefit of being applicable to anybody with eyes—you see where you are in a cycle and know how long until you reach a different moon phase.  When measuring longer spans such as seasons or years, however, there are disparities.

The solar year…okay, there are a couple of different ways to measure this, too. You will likely be familiar with the Gregorian calendar – the modern western standard – which uses the tropical solar calendar.  By this measure, the solar year is roughly 365.24 days long.  Twelve lunar months fit within a solar year with 11 days to spare.  The discrepancy of a few days per year adds up, so that after a decade, a given lunar cycle in a 12-month year has crept into another season.  The lunar cycles and solar cycles take some 33 years to match up.

Natural cycles don’t care about conforming to our need for whole numbers. 

People across the world have developed different ways of organizing a year.  Going beyond the lunar calendar, we’ve developed several versions of a lunisolar calendar, which marries the lunar and solar timekeeping systems.  Months still follow the lunar cycle.  Generally speaking, some years have 12 months and others have 13. Determining when to apply these “leap months” requires some calculation to determine and a certain level of education to understand.   

Finally, the solar calendar follows the sun’s apparent cycle through the heavens with no concern for lunar position.  There are several, but the aforementioned Gregorian calendar should be most familiar to you. It still uses months, and the months are similar in length to a lunar month, but lunar cycles drift through our Gregorian months with no real connection.  Well, with one exception: Christian churches overlay a lunar algorithm to determine the dates of certain movable feasts – Easter chief among them.

 There are probably over a dozen calendars – solar, lunar, and lunisolar — in use today, and many, many more during the course of human history.  But I’d wager that the basis for each of them lay in one or both of our most prominent celestial bodies: the moon and the sun.

The Immortal Complaint

This is a tale of two fellows linked by a letter of complaint: from Nanni the disgruntled customer, and Ea-nasir the merchant.  It seems Nanni paid good money for products, and when his assistant went over to collect the items, he was offered third-rate merchandise and treated rudely.  The irate customer wrote on every bit of the complaint form, detailing his many injuries at the hands of this shameful purveyor of shoddy goods. He made it absolutely clear that in the future the goods would be brought to Nanni’s  own yard, and they’d better be top notch or he wasn’t paying.

The letter was found in Ea-nasir’s house along with some others, but we don’t know if Nanni got satisfaction.  We can’t ask him, because Ea-nasir has vanished, along with his business, like dew on a desert breeze. 

The letter was written on a clay tablet in Akkadian cuneiform, around 1750 BCE.

My son, who does his best to keep his old man appraised of all the geek things, sent me a meme involving Ea-nasir.  It turned out to be but one of many, framed around “The World’s Oldest Complaint Letter”.  There are also quite a few videos of variations of the same joke: Customer service hasn’t changed in four thousand years.

By Zunkir – Own work, CC BY-SA 4.0

While I can appreciate the humor (such that it is), this isn’t what struck me about this artifact.  It was the names.  The further back you look in time, the fewer individuals can be seen.  A thousand years back, we have records of the heads of state or notable churchmen and nobles whose names graced deeds or court records archived in stone buildings.  Two thousand years ago, writing was perhaps more common in some locales but still available to a minuscule fraction of the general population, and almost no parchment or papyrus survived the ages; even the names of the mighty which were chiseled on stone  are now too often weathered to obscurity.

Farther still, when writing was necessary for civilization to function yet still mystic enough to be wielded by specialists,  a powerful man at the apex of a city-state would use some of his power to immortalize his likeness and his name on a stone tablet, or perhaps have the embellished story of his military victories drawn on baked clay; like as not such mementos would be destroyed or lost when the next big man came to power.

Yet the astoundingly short list of identities to survive the rise and fall of kingdoms, countries, languages and cultures, include two folks who were not great warriors, not great lords, not godspeakers.  No, they were tradesfolk, strictly middle-tier. 

To put it in perspective, imagine that millennia from now the museum talks mention the names of folks known in the North American continent: maybe half a dozen presidents, a few prime ministers, a few military figures and one or two social leaders.  And on a shelf in one corner of museum is piece of paper – a miraculous missive to one Crazy Eddie, purveyor of used vehicles, from an angry Frank.


I was reminded of a scene in the movie The 13th Warrior.  Buliwyf, the illiterate leader of a warband, had become intrigued by a civilized fellow’s magical ability to write (or as he put it, “draw words”).  As he lies on his deathbed, he hinted to his friend his last request: “A man might be thought wealthy if someone were to draw the story of his deeds, that they may be remembered.”  By that mark, Nanni and Ea-Nasir only have loose change in their accounts, but they remain among the richest people of the Bronze Age.

Additional Information:

See the full translation of the tablet.

Buliwyf’s request