Celtic Symbolism: The Gaulish Lunisolar Calendar - Lunar Influences and System Properties

The continental Celtic calendar as reconstructed from the calendars of :
1- Coligny
2-Villards d'Heria

1- The Gaulish Coligny calendar was found in Coligny, Ain, France (46°23′N 5°21′E) near Lyon in 1897, along with the head of a bronze statue of a youthful male figure. It is a lunisolar calendar. It is now held at the Gallo-Roman Museum of Lyon.

It was engraved on a bronze tablet, preserved in 73 fragments, that originally was 1.48 m wide and 0.9 m high. It is written in Latin inscriptional capitals, and is in the Gaulish language . The restored tablet contains sixteen vertical columns, with 62 months distributed over five years.

Overview of the re-assembled tablet

2- The Villards d'Heria is a similar calendar, found nearby at Villards d'Heria (46°25′N 5°44′E) is only preserved in eight small fragments. It is now preserved in the Musée d'Archéologie du Jura at Lons-le-Saunier.

The Lunar Influence On The Calendar Format

The Coligny Calendar is an attempt to reconcile both the cycles of the moon and sun, as is the modern Gregorian calendar. However, the Coligny calendar considers the phases of the moon to be important, and each month always begins with the same moon phase. The calendar uses a mathematical arrangement to keep a normal 12 month calendar in sync with the moon and keeps the whole system in sync by adding an intercalary month every 2½ years.

The Coligny calendar registers a five-year cycle of 62 lunar months, divided into a "bright" and a "dark" fortnight (or half a moon cycle) each. The months were possibly taken to begin at full moon, and a 13th intercalary month was added every two and a half years to align the lunations with the solar year.

The astronomical format of the calendar year that the Coligny calendar represents may well be far older, as calendars are usually even more conservative than rites and cults. The date of its inception is unknown, but correspondences of Insular Celtic and Continental Celtic calendars suggest that some early form may date to Proto-Celtic times, roughly 800 B.C.E. The Coligny calendar achieves a complex synchronization of the solar and lunar months. Whether it does this for philosophical or practical reasons, it points to considerable degree of sophistication.

The Calendary System Properties

It was a lunisolar calendar, attempting to synchronize the solar year and the lunar month.

• The months were lunar. Scholars disagree as to whether the start of the month was the new moon or the full moon, or per Pliny and Tacitus perhaps even the First Quarter.

• The common lunar year contained 354 or 355 days.

• The calendar year began with Samonios, which is usually assumed to correspond to Old Irish Samhain, giving an autumn start to the year. However, as Samon is Gaulish for summer (Lambert p. 112), this assumed start is disputed. Le Contel and Verdier (1997) argue for a summer solstice start of the year. Monard (1999) argues for an autumn equinox start. Bonsing (2007) argues for a May beginning consistent with Irish Beltaine, and Fennian literature, notably Joyce (2000).

• The entry TRINOX[tion] SAMO[nii] SINDIV "three-nights of Samonios today") on the 17th of Samonios suggests that, like the Irish festival of Samhain, it lasted for three nights. The phrase *trinoxtion Samonii is comparable to a Gaulish festival mentioned in a 1st century AD Latin inscription from Limoges, France, which mentions a "10 night festival (*decamnoctiacon) of (Apollo) Grannus" (POSTVMVS DV[M]NORIGIS F(ILIVS) VERG(OBRETVS) AQVAM MARTIAM DECAMNOCTIACIS GRANNI D[E] S[VA] P[ECVNIA] D[EDIT] )[4]

• the solar year was approximated by the insertion of a 13th intercalary month every two and a half years (unlike the Islamic calendar, where the calendar year keeps shifting in relation to the solar year). The additional months were intercalated before Samonios in the first year, and between Cutios and Giamonios in the third year. The name of the first intercalary month is not known with certainty, the text being fragmentary; the second intercalary month is Ciallos bis Sonnocingos (Lambert p. 116)

• The months were divided into two halves, the beginning of the second half marked with the term atenoux or "renewal"[5] (cf. Old Irish athnugud "renewal"). The basic unit of the Celtic calendar was thus the fortnight or half-month, as is also suggested in traces in Celtic folklore. The first half was always 15 days, the second half either 14 or 15 days on alternate months (similar to Hindu calendars).

• Months of 30 days were marked matus, lucky. Months of 29 days were marked anmatus, unlucky.

• A simple five year cycle would be insufficiently accurate; the sequence of intercalary months is completed every thirty years, after five cycles of 62 lunations with two intercalary months each, and one cycle of 61 lunations, with a single intercalary month, or after a total of 11 intercalary months. This assumes that there are exactly 371 lunations in 30 years, which is accurate to a one day every 20 or 21 years on average (this is less accurate than the Julian calendar, which shifts a day in about 130 years, but which ignores lunar months). It may be assumed that the "30 years cycle" was not prescriptive, and that an extra month would have been omitted as the need arose (i.e. some 300 years after the calendar's inception).