What’s the date?

Today, I accidentally stumbled upon this entry on Onthisday.com:

Of course, the day wasn’t March 28 for Thales. It would have been some ancient Greek month — but which one? This question led me down a rabbit hole that you are welcome to follow yourself. I’ll put some links at the end of this article and you can meet me right there, at the bottom of the rabbit hole.

First the year: it’s obvious that the Greeks, not knowing the precise future date of the birth of Christ, wouldn’t have named their year 585 BC. But what then?

Turns out, in classic times, they used to count 4-year periods, from one Olympiad to the next. This could work nicely, since the first Olympic Games took place in 776 BC, long before any of the great moments of classic Greek civilisation. Unfortunately, this way of counting the years was only established by a philosopher called Hippias of Elis in the 5th century, and so wouldn’t have been used in 585 BC. I couldn’t find anything about the calendar used in Miletus in Thales’ time, except that it was Thales himself (or, according to some sources, a student of Plato’s academy, Callippus of Cyzicus) who determined that the true length of a year was not 365 days but a quarter of a day more than that. So whatever calendar was in use before and during Thales’ time, would have been increasingly wrong as the years passed, and would have been corrected ad-hoc from time to time, whenever people noticed that it was still snowing in spring.

Ancient Greek calendars

The months were, like in all ancient cultures, aligned with the moon’s phases. In German, even today, the word for “month” is “Monat,” which is related to “Mond,” the word for moon. Unfortunately, the moon’s phases again don’t align with the length of a solar year, so from time to time people dropped a month to make their calendar fit the actual season as they saw it played out in the nature around them.

Let’s not even talk about weeks. The week is a Judeo-Christian concept, derived from the Biblical story of God creating the world in seven days and resting on the last day, which inspired Judeo-Christian-Muslim societies to do the same and declare one day of the week the resting day; depending on the flavour of one’s faith, it would be either the Friday, the Saturday or the Sunday. The ancient Greeks used to divide the month more practically into three ten-day periods, roughly following the phases of the moon throughout its …

Read the full article which is published on Daily Philosophy (external link)