The Coligny Tablet

A Surviving Celtic Calendar

A number of engraved copper-alloy fragments were discovered in 1897 in ancient silvan surroundings some fifteen miles north-east of Bourg-en-Bresse, France. They were quickly recognised as pieces of a single, large bronze tablet, which measured some 5 feet wide by 3½ feet in height (approx. 1.5 x 1 metres) when the fragments were reassembled. The restored tablet contains tabular information arranged in sixteen vertical columns, with what appear to be observations on the weather being systematically recorded.

The French archaeologist J. Monard studied the inscriptions for a number of years, and came to the conclusion that the Coligny tablet represents the best known example of a Celtic calendar. He further speculated that the information recorded on the calendar was compiled by Gallic druids who wished to preserve the ancient Celtic system of timekeeping, at the time when the Julian calendar was being rigorously enforced throughout the entire Roman empire, around the turn of the first century AD.

Several important features of the ancient Celtic calendar were revealed or confirmed on the Coligny tablet;

  1. The Celtic month started at the full-moon, rather than the new-moon, probably because the full-moon is easier to observe and record. Each month alternately contained 29 or 30 days, making a Celtic year 354 days in length.
  2. The calendar took into account the differing time periods taken by the moon and the sun to circle the earth (prevalent geocentric terminology used), and reconciled the differences by inserting an extra month on a regular cycle. This method of intercalation meant that most years contained twelve months, and approximately every third year contained thirteen months. This extra month was called Mid Samonios, and was intercalated between Cutios and Giamonios in the calendar.
  3. The month was divided into two parts, a ‘light’ half, and a ‘dark’ half, each approximately of two week’s duration; the division marked by the word Atenoux ‘returning night’ on the Coligny fragments. This confirms that the new-moon also played a part in the Celtic calendar, and very likely had some religious significance. This also bears-out the impression we get from the traditional Celtic folk-stories which maintain that the normal period of Celtic timekeeping was the fortnight.
  4. By extrapolation, the calendar also confirms that the Gallic druids maintained a thirty-year cycle of timekeeping, comprising five cycles of 62 lunations and one cycle of 61 lunations, during which period, eleven intercalary months would be added.

The Celtic Months

SamoniosOct / NovSeed-fall
DumanniosNov / DecThe Darkest Depths
RiurosDec / JanCold-time
AnagantiosJan / FebStay-home-time
OgroniosFeb / MarTime of Ice
CutiosMar / AprTime of Winds
GiamoniosApr / MayShoots-show
SimivisioniosMay / JunTime of Brightness
EquosJun / JulHorse-time
ElembiuosJul / AugClaim-time
EdriniosAug / SepArbitration-time
CantiosSep / OctSong-time

The above table, particularly the derivation of the names of the Celtic months, is taken from the superb book The Celtic Tradition by Caitlin Matthews.

Two of the main Celtic religious festivals Beltain and Lughnasadh were indicated on the Coligny calendar by small sigils, and each year started with the month of Samonios, during which period the festival of Samhain was celebrated. A fourth major festival Oimelc, which occurred during mid winter, is not indicated on the tablet.

Though not confirmed by the Coligny inscriptions, we also know that in accordance with general Celtic custom, which was itself adopted from the ancient Greek observance, each day was reckoned to last from sunset to sunset; not midnight to midnight as our modern Roman calendar dictates.