Thursday, November 28, 2013

Origns of our Calendar - Part I

Ever wonder where the names of our months came from?  Specifically, have you ever wondered why September, October, November, and December have prefixes that mean 7 (septem), 8 (octo), 9 (novem), and 10 (decem) in Latin even though they are the 9th, 10th, 11th, and 12th months of our calendar.  No?  Just me?  Oh well, I'll explain anyway.

The original Roman Calendar was a lunar calendar similar to that used by the earlier Greeks. Since the time between new moons averages 29.5 days, months alternated with either 29 or 30 days. The first day of the month, the kalends (from which we get “calendar”) started with the first appearance of the crescent after the new moon, the nones were the two days of the quarter moons, and the ides (in the middle of the month) were the days of the full moon.
   Who is it in the press that calls on me?
   I hear a tongue shriller than all the music
   Cry "Caesar!" Speak, Caesar is turn'd to hear.
   Beware the ides of March.
   What man is that?
   A soothsayer bids you beware the ides of March.

Julius Caesar (Act 1, scene 2, 15-19)
William Shakespeare

The Murder of Caesar
Karl von Piloty (1826–1886)

At some point in history, this traditional lunar calendar was replaced by a solar calendar roughly in line with the length of the tropical year (the length of time from equinox to equinox). It was attributed to Romulus – the mythical character who, along with his twin brother Remus, was fathered by the god Mars, abandoned as an infant to die, suckled and raised by wolves, and founded the city of Rome around 753 BCE.

Romulus, vainqueur d'Acron, porte les dépouilles opimes au temple de Jupiter
Jean Auguste Dominique Ingres (1780–1867)

This Roman calendar started on March 1, the month containing the vernal equinox, and consisted of 10 months:
   Martius (31 days) Honors Mars, god of war (when armies marched off to war)
   Aprilis (30 days) From Latin aperire or “open” (leaf buds are opening)
   Maius (31 days) Honors Maia, Greek goddess of fertility (flowers are blooming)
   Junius (30 days) Honors Juno, goddess of marriage (why we have June weddings)
   Quintilis (31 days) Latin for five (fifth month)
   Sextilis (30 days) Latin for six (sixth month)
   September (30 days) Latin septem or seven (seventh month)
   October (31 days) Latin octo or eight (eighth month)
   November (30 days) Latin novem or nine (ninth month)
   December (30 days) Latin decem or ten (tenth month)
See, September, October, November, and December once did make sense!
Anyway, if you're like me, you'll have added up those numbers and see that they only add up to 304 day. The Romans dealt with this by having an unnamed and unnumbered winter period of about 61 days in the period of time we now call January and February.

King Numa Pompilius conversing with the nymph Egeria in her grotto
Bertel Thorvaldsen (1770-1844)
Around 713 BCE, the legendary(?) second king of Rome (after Romulus), Numa Pompilius, is credited with adding two months to the calendar, altering some of the days of each month, giving the following:
   Ianuarius (29 days) Honors Janus, the two-faced god of gates and doorways
   Februarius (28 days) Latin Februra – a day of purification held during late winter
   Martius (31 days)
   Aprilis (29 days)
   Maius (31 days)
   Junius (29 days)
   Quintilis (31 days)
   Sextilis (29 days)
   September (29 days)
   October (31 days)
   November (31 days)
   December (29 days)
This add up to 355 days, still 10 days off from the length of the solar year. To accommodate things, a complicated method was used. For religious reasons, February was split into two parts – days 1 to 23 and days 24 to 28.  Every once in a while, a leap month of 27 days (Mensis Intercalaris) was inserted between the two halves of February.
The decision to add the intercalary month was that of the Pontifex Maximus and done every 2-3 years. This position was a political appointment and many in the position abused their power by lengthening the year when it didn’t need to be in order to keep their political allies in power. By the time Julius Caesar was Pontifex Maximus around 46 BCE, the calendar was almost a full season (80 days or so) off from the date of the Vernal Equinox!

Next post - Julius Caesar's calendar reform!

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