Prior to the reforms of Julius Caesar, there has been considerable speculation on the form of the Roman Calendar. So much is unknown. While some are convinced that it was a lunar calendar, others claim that it was more of a solar calendar. Some believe that the year length was 304 days, others claim that because it was a lunar calendar, the start of the month began at the New Moon and because the average lunar cycle is 29.53059 days, the month lengths are either 29 or 30 days and thus the year length was 354 days. We do know that the Romans added an intercalary month every so often, while some have suggested that it was really two intercalary months of unknown month length.
We know that the Romans inherited much of Greek philosophy and thought. The Greeks themselves were fond of the Metonic Cycle, but we are uncertain if the Romans truly consistently applied this cycle to their calendar. The Metonic Cycle is simply a recognition of the Greek love of patterns in astronomical observation. Every 19 years, the phases of the moon line up again. (19 years = 235 lunar (synodic) months).
We know that the Romans needed to recalibrate their calendar every so often and added an intercalary month just for this purpose. But the rules for its application and when it was applied is totally unknown. Perhaps the greatest frustration is understanding the rules, is the fact that ancient Roman authors wrote down what they thought was common practice for the calendar, and they disagree amongst each other. An historian like Plutarch (born c. AD 50) did not live through the calendar reforms of Julius Caesar (45 BC).
We can see remnants of a lunar calendar in the Ancient Roman nomenclature of three dates:
|
Date
|
Meaning
|
| Kalends |
This was the first day of the month and the start of the New Moon. |
| Nones |
This would be the First Quarter Moon. Non is a Greek prefix meaning 9. This is the 9th day (counting backwards and inclusively) from the Ides. |
| Ides |
This would be the Full Moon, the mid point of the month. |
It was the job of the head priest or Pontifex Maximus to adjust the calendar. But by the time Julius Caesar seized power in Rome, the seasons were out of alignment. Months associated with spring were actually occurring the winter. This problems implies that although the ancient Roman calendar may have begun as a lunar one, secular need was turning it into a solar one. An agrarian based culture relies on a solar calendar to help with the planting and harvesting of crops.
The reform of Julius Caesar was a massive one. Taking on the role of Pontifex Maximus, Caesar saw it as his role to correct the calendar. The Calendar took on a totally new shape, month lengths were alerted, month positions were changed and a month was renamed.
Before Julius Caesar, the ancient Roman calendar ended with the month of Februarius (February). The order of the months were:
|
Month |
Meaning |
| Martius |
for Mars, God of War. Nowadays called March
|
| Aprilis |
meaning to open possibly in reference to the opening of flower buds. (sacred to Venus) Nowadays called April |
| Maius |
for Goddess Maia, the wife of Mars (Nowadays called May) |
| Junius |
for Goddess Juno, the Wife of Jupiter (Nowadays called June) |
| Quinctilis |
later renamed to Julius (July) in honor of Julius Caesar (sacred to Jupiter)
|
| Sextilis |
the 6th month (sacred to Ceres) |
| September |
the 7th month (sacred to Vulcan) |
| October |
the 8th month (sacred to Mars) |
| November |
the 9th month (sacred to Diana) |
| December |
the 10th month (sacred to Vesta) |
| Januarius |
the 11th month (sacred to Ianus) |
| Februarius |
the 12th month (sacred to Juno Februra)
|
To accomplish this massive change and to convert the calendar from a cacophony of irregular rules to a consistent solar calendar, Julius Caesar had some 67 days added to the calendar in the year 46 BC. His calendar rules took place in the following year 45 BC. So that 45 BC could begin at a known starting point, 46 BC was a strange year of 15 months. This was a one-time correction.
Caesar next turned his attention to domestic reforms. First he reorganized the Calendar which the Pontiffs had allowed to fall into such disorder, by intercalating days or months as it suited them, that the harvest and vintage festivals no longer corresponded with the appropriate seasons. He linked the year to the course of the sun by lengthening it from 355 days to 365, abolishing the short extra month intercalated after every second February, and adding an entire day every fourth year. But to make the next first of January fall at the right season, he drew out this particular year by two extra months, inserted between November and December, so that it consisted of fifteen, including the intercalary one inserted after February in the old style. --Suetonius (translated by Robert Graves)
He also paid homage to their lunar tradition by beginning his reform at the New Moon. The month that began with the New Moon in 45 BC was (Januarius). Thus, January was reordered to the beginning of the reform year.
Julius Caesar's reform had the months and their month lengths this way:
|
Month |
Month Length |
| Januarius |
31 days |
| Februarius |
29/30 days |
| Martius |
31 days |
| Aprilis |
30 days |
| Maius |
31 days |
| Junius |
30 days |
| Quinctilis |
31 days |
| Sextilis |
30 days |
| September |
31 days |
| October |
30 days |
| November |
31 days |
| December |
30 days |
We can see embedded in the names of the month their original position
|
Month
|
Latin Meaning
|
Comments
|
| Sextilis |
Sex = 6 |
but it became the 8th month (later renamed by Augustus) |
| September |
Septem = 7 |
but now its the 9th month |
| October |
Octo = 8 |
but now its the 10th month |
| November |
Novem = 9 |
but now its the 11th month |
December |
Decem = 10 |
but now its the 12th month |
Since Julius Caesar converted the calendar to a solar one, the position of the Kalends, Ides and Nones lost their attachment to the moon. Instead of dates heralding the position of the moon, they simply became dates. The Kalends were always the first of the month, but the first of the month was not necessarily a New Moon. The Ides were fixed to the following dates:
|
Month |
Date of Ides |
Date of Nones |
| Januarius |
13th |
5th |
| Februarius |
13th |
5th |
| Martius |
15th |
7th |
| Aprilis |
13th |
5th |
| Maius |
15th |
7th |
| Junius |
13th |
5th |
| Quinctilis |
15th |
7th |
| Sextilis |
13th |
5th |
| September |
13th |
5th |
| October |
15th |
7th |
| November |
13th |
5th |
| December |
13th |
5th |
Every British school child was taught the following ditty about the placement of the Ides:
In March, July, October, May
The Ides fall on the 15th day
The Nones the 7th.
The rest besides take 2 days less
For Nones and Ides.
Thus, the Ides of March was March 15, whereas the Ides of February was February 13. Another change that was implemented by Julius Caesar was to rename the month of Quinctilis after himself. The year, 45 BC was the very first year these massive changes took effect (including the renaming of Quinctilis). Julius Caesar lived long enough to see the month of Julius only once: he was assassinated in the following year on the Ides of March.
Perhaps the one change that stood the test of time and was only proved wrong some 1500 years later was the simple leap year rule. Julius Caesar called for the addition of one date every 4 years. In his day, Februarius would go from a 29 day month to a 30 day month.
The Emperor Augustus was the next to implement additional changes to the calendar. These changes occurred at 8 BC. What changes other emperors tried to implement were reversed after their reign. Yet those changes were trivial compared to the fundamental error that a leap day every 4 years was simply wrong. The next person to take up the challenge of calendar reform was Pope Gregory XIII in 1582.
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