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 (Lambert, Pierre-Yves, La langue gauloise, Editions Errance, 2nd edition, Paris, 2003, p.111) or approximately 5 feet (1.5 m) wide by 3½ feet in height. Based on the style of lettering and the accompanying objects, it probably dates to the end of the 2nd century AD. It is written in Latin inscriptional capitals and is in the Gaulish language (Duval, P.M. and Pinault, G., Recueil des inscriptions gauloises, Tome 3: Les Calendriers (Coligny, Villards d’Heria), CNRS, Paris, 1986, pp. 35-37.). The restored tablet contains sixteen vertical columns, with 62 months distributed over five years.
The French archaeologist, J. Monard, speculated that it was recorded by druids wishing to preserve their tradition of timekeeping in a time when the Julian calendar was being imposed throughout the Roman Empire. However, the general form of the calendar suggests the public peg calendars (or parapegmata) found throughout the Greek and Roman world (Lehoux, D. R. Parapegmata: or Astrology, Weather, and Calendars in the Ancient World. PhD Dissertation, University of Toronto, 2000).
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 Continental Celtic calendar as reconstructed from the calendars of Coligny and Villards d’Heria had the following 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 (October 31st), giving an autumn start to the year. However, as Samon is Gaulish for summer (Lambert, Pierre-Yves (2003). La langue gauloise. Paris, Editions Errance. 2nd edition. ISBN 2-87772-224-4. Chapter 9 is titled “Un calandrier gaulois.”), 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] )
**the solar year was approximated by the insertion of a 13th intercalary month every two and a half years. 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” (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 per cycle, 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).
Gaulish Calendar in Historical Sources
Pliny the Elder
The Natural History of Pliny the Elder states, in a discussion of Druidic gathering of mistletoe (Pliny NH 16.95):
The mistletoe, however, is but rarely found upon the robur (Oak); and when found, is gathered with rites replete with religious awe. This is done more particularly on the sixth day of the moon, the day which is the beginning of their months and years, as also of their ages, which, with them, are but thirty years. This day they select because the moon, though not yet in the middle of her course, has already considerable power and influence; and they call her by a name which signifies, in their language, the all-healing.
This comment supports the grouping of five-year Coligny calendar periods into thirty-year ages, with the loss of one intercalary month per age to more accurately align the solar and lunar cycles.
Julius Caesar in The Gallic Wars states (Caesar, DBG 6.18) that days, months, and years start with a dark half followed by a light half.
All the Gauls assert that they are descended from the god Dis, and say that this tradition has been handed down by the Druids. For that reason they compute the divisions of every season, not by the number of days, but of nights; they keep birthdays and the beginnings of months and years in such an order that the day follows the night.
This is consistent with a month starting at the dark of the moon, or at the sixth day of the moon per Pliny (Natural History); it is inconsistent with a month starting at full moon.
The following Etymologies, unless otherwise noted, are taken from Xavier Delamarre, Dictionnare de la langue gauloise, 2nd edition, Editions Errance, 2003.
Samonios – “Month Belonging of Summer.” Likely an n-stem derivative (with a suffix of appurtenance, -io-) of the Common Celtic root *samo- “summer” found in Old Irish sam, Welsh haf. Cf. Old Irish Samain “(festival of the) First of November”, “All-Hallows/All-Saints day” and Mithem, Mithemain “Mid-summer, month of June”, Middle Welsh Meheuin “June” (both from Common Celtic *Medi[o]-samVn [V=”vowel”, likely -o- or -u-]-), as well as Old Irish Cétamuin “Month of May”, “First of May”, “May Day” (alternate name for Beltain), Welsh Cyntefin “month of May” (both from Common Celtic *kintu-samonis “beginning of Summer”). An alternate proposal is that the root of the name is Common-Celtic *sem- “one, same, together”, making it the “Month of Assembly.”
Duman(n)(ios) – “Month of (religious) Fumigation”? Cf. Latin fūmus “smoke”, Sanskrit dhūmah “smoke”, Greek θύμος (thūmos) “soul, life, passion; anger, wrath” (also θύμιάω [thūmiaoo] “to burn, as incense”, θύμα [thūma] “sacrificial offering”).
Riuros – “Thick/Fat/Large month”? Possibly cognate with Old Irish remor “stout, thick, fat”, Welsh rhef “thick, stout, great, large” (in which case, the original form may have been *Remros, with later shift of -e- to -i- [compare the alternation between Semi- and Simi- in Semuisonna] and lenition of internal -m-). Some scholars alternately suggest a connection with Old Irish réud, Welsh rhew “cold”.
Anagantios – “Month in which One Does Not Travel”, “Non-itinerant month?” Composed of a Common Celtic negative prefix *an- and an agentive noun *agant- based on the root *ag- “to go, to conduct, to lead”. Cf. Old Irish ag “to go, do, conduct”, Welsh agit “goes”.
Ogron(n)(i)(os) – “Cold Month”. An n-stem derivative of the Common Celtic root *ougros “cold”. Cf. Old Irish úar, Welsh oer. The root *oug- may be compared to Armenian oyc “cold”, Lithanian auksts “cold”, and Latin a(u)ctumnus “autumn”.
Cutios – unknown etymology. Some have compared it to the obscure Greek month name Κοούτιος (Kooutios) in the Lokrian calendar from Chaleion (which may = October–November).
Giamonios “Month belonging to Winter”. An n-stem derivative (suffix of appurtenance -io-) derived from the Common Celtic root *giįamo- “winter”. Cf. Welsh gaeaf, Breton goañv, Old Irish gaim “winter”, Gamain “month of November” (also, a “yearling calf” [a calf that is one winter old]).
Simiuisonna (or Semiuisonna) – unknown etymology. Perhaps Common Celtic *sēmi- “half” plus *ues- “Spring(time)” or a compound containing a feminine form of the word for “sun”, *sonna (see Sonnocingos below).
Equos – etymology unknown. Some scholars have connected it with the word for “horse” in Celtic languages, Common Celtic *ekWos, Old Irish ech, Welsh eb- (found only in ebol “pony”, compound words such as eb-rwydd “fast/quick/ready”, eb-ran “fodder”, and the place name Mynydd Epynt), but there is some disagreement over this, since one would expect the form to be *Epos in a P-Celtic language such as Gaulish, in which personal, divine and place names containing the P-Celtic form *epo- are widely attested (some scholars acknowledge this point, but propose that the Calendar may contain Q-Celtic dialectal features, or archaisms dating to a time before Proto-Celtic -kw- became -p- in Gaulish; yet the Calendar does display P-Celtic words such as prinni, pog-, and peti, which argues against this).
Elembiu – “Month belonging to the Deer”. From the Proto-Indo-European root *elen-bho- “deer”, which gave us English lamb and the Greek έλαφος (elaphos), Έλαφιον / Έλαφιος (Elaphion / Elaphios), “Month belonging to the Deer” (called Έλαφηβολιών [Elaphebolion] “Month of the Deer-hunt” in the Attic Calendar, equivalent to March–April). An alternate form of the PIE root, *elen-, gave us Welsh elain and Old Irish elit, “doe, hind; young deer”.
Aedrini(os) – Bright (or Hot) Month”; cf. Old Irish aed “fire”, “heat”, Greek αἰθήρ (aithēr) “bright sky, upper air, ether”. Ultimately from the Proto-Indo-European root *aidh- which also gave us Latin aestas “Summer”.
Cantlos – perhaps “Song month”; cf. Welsh cathl “song”, Breton keñtel “lesson”, Old Irish cétal.
Sonnocingos – “Sun’s march”; cf. Welsh huan “sun” and Old Irish cinged “to walk, march”. May not be the actual name of the intercalary month, but rather some term applied to it (Delamarre suggests perhas “sun’s march = “a year”).