I wanted to make a dedicated post regarding the calendar used in ancient times. It is such a very different way to measure time for each month (according to the moon), compared to how we keep our time now. Late yesterday afternoon looking up at the moon (a waxing crescent) had me pondering that ancient way of keeping time.
Based on Wikipedia we can deduce that is is very likely that Epicurus would have used the Attic calendar since he was living in Athens. But before he lived in Athens, he may have used different calendars, since it also says this:
The Attic calendar or Athenian calendar is the lunisolar calendar beginning in midsummer with the lunar month of Hekatombaion, in use in ancient Attica, the ancestral territory of the Athenian polis. It is sometimes called the Greek calendar because of Athens's cultural importance, but it is only one of many ancient Greek calendars.
Although relatively abundant, the evidence for the Attic calendar is still patchy and often contested. As it was well known in Athens and of little use outside Attica, no contemporary source set out to describe the system as a whole. Further, even during the well-sourced 5th and 4th centuries BC, the calendar underwent changes, not all perfectly understood. As such, any account given of it must be a tentative reconstruction.
The Greeks, as early as the time of Homer, appear to have been familiar with the division of the year into the twelve lunar months but no intercalary month Embolimos or day is then mentioned, with twelve months of 354 days. Independent of the division of a month into days, it was divided into periods according to the increase and decrease of the moon. Each of the city-states in ancient Greece had their own calendar that was based on the cycle of the moon, but also the various religious festivals that occurred throughout the year.
Wikipedia goes on with this:
Monthly and annual festivals were not usually allowed to fall on the same days so every festival month had an opening phase with exactly recurrent practices and celebrations while in the body of each month was a unique schedule of festival days.
A parallel function of this calendar was the positioning of the perhaps 15 or so forbidden days on which business should not be transacted.
Rather than considering the month as a simple duration of thirty days, the three-part numbering scheme focuses on the moon itself. In particular the waning days 10–2 and the waxing days 2–10 frame the crucial moment where the moon vanishes and then reappears.
A date under this scheme might be "the third (day) of Thargelion waning", meaning the 28th day of Thargelion.
Names of the days of the month
new moon 11th later 10th 2nd waxing 12th 9th waning 3rd waxing 13th 8th waning 4th waxing 14th 7th waning 5th waxing 15th 6th waning 6th waxing 16th 5th waning 7th waxing 17th 4th waning 8th waxing 18th 3rd waning 9th waxing 19th 2nd waning 10th waxing earlier 10th old and new [moon]
To summarise the days with special names.
- The first day: noumenia, or new moon.
- The last day: henē kai nea, the "old and the new".
- The 21st day: "the later tenth". The Attic month had three days named "tenth" (equivalent in a straight sequence to the 10th, 20th, and 21st days). These were distinguished as
- 10th: "the tenth (of the month) waxing"
- 20th: "the earlier tenth" (i.e. waning)
- 21st: "the later tenth" (i.e. waning)
This strange juxtapositioning of the two days called the tenth, the earlier and the later, further highlighted the shift into the moon's waning phase.
When a month was to last 29 instead of 30 days (a "hollow" month), the last day of the month ("the old and new") was pulled back by one day. That is to say, the "second day of the waning month" (the 29th in straight sequence) was renamed as month's end.
Now I want to say that as I was looking at a moon chart, and remembering past times of gazing at the moon, it came to me that it is difficult to know exactly when the moon is completely full by the ordinary eyes -- so then this counting would only apply to days when you can descern clear changes in the size of the moon.
And I would like to go on to suggest a way of counting which may or may not make sense (but is different than the Wikipedia article) and this way of counting is according to what a human eye can see happening with the moon. My idea would be that you start counting on the day that you see a large enough crescent -- that would be waxing day 1, waxing day 2, etc. and then you continue to count to waxing day 10 (which would be called the "earlier 10th", the following day would be considered full moon of which there would be several days (as you can see from the chart above, that the moon is nearly full both before and after the actual full moon). Then on the day when you can descern that the moon is waning you begin counting waning day 1, waning day 2, etc. and continue counting up (not down) and so this would give you the "later 10th".
But this is just my own idea, my own imagination of trying to make sense of things.
Although now thinking further, we do actually know when the moon is full because it rises opposite of the sun setting. So not sure than if my idea makes any sense to count the way I suggest.
Nate what do you think?
By my counting then, the 20th (which would be the 2nd 10th) would fall on the last day of a visible waning crescent. (And this is different than what Nate calculated on another thread).
Edit note: Dec.1, 2022 -- I have now resigned myself to the Wikipedia version of the counting of the days of the month (and I found nothing to support my own idea). The rest of this thread goes on with a little bit of a back and forth between this and the Wikipedia counting. And also contains Nate's nice graphic design, in multiple colors.