"Who can tell the Phases of the Moon?" - Song of Amergin

| Introduction | The Pleiades Cycle | The Coligny Tablet | Samhradh | Geimhreadh |
| Celtic Calendar 2008 | The Southern Seasons Celtic Calendar 2008 | Celtic Calendar Forum |

 

The Coligny Tablet

samon duman rivros anagantios ogronnos cvtios || giammon semivisonna equos elemivios aedrini cantlos

This section looks at the structure of the Celtic calendar as revealed by the 1st century BC bronze calendar inscription found at Coligny, France toward the end of the nineteenth century. The tablet, also called the 'Coligny Calendar' or the 'Gaulish Calendar', reveals a sophisticated calendar system, which by comparison to myth and records of Wales and Ireland is shown to have been shared across the Celtic world. It is of historical interest to see that after the conquest of Gaul, Julius Caesar gathered "the best scholars and mathematicians of the day" (Plutarch, Life of Caesar, 59) to standardise and correct the Roman calendar, for "there had been great confusion among the Romans with regard to the relation of the lunar to the solar year, with the result that the festivals and days of sacrifice gradually got out of place [in the Roman system; and] the priests ... would suddenly insert in the calendar the intercalary month known as Mercedonius" (Plutrach, Life of Caesar, 59). After nearly a decade in the Celtic lands, Caesar would have become familiar with the Celtic system, and perhaps he was inspired to repair the Roman system. He set new year's day at January 1, around mid-winter, and as the Celtic lands came under Roman rule so too did they need to adapt their own festivals to the Roman calendar.

Who can tell the Ages of the Moon?

The Druid, Amergin invoked the calendar at the arrival of the Tuatha de Danaan in Ireland (Gregory, 1904), showing it to be of fundamental importance to Celtic society and among the principle foundations of its success. The Druids, as recorded by Pliny the Elder in the first century AD, called the moon "in their language omnia sanantem the all-healing", marking her cycle from the first quarter phase "the day which is the beginning of their months", on the basis that "the fifth day of the moon, [in Greek reckoning, is when] the moon, though not yet in the middle of her course, has already considerable power and influence" (Pliny, Natural History, 17.95).

On the first quarter phase, the moon is at its azimuth at sunset, which is when the Celtic reckoning of daily periods commences: Caesar recorded this in 53BC during the Roman conquest of Gaul, where he reported they calculate "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" (Caesar, Bellum Gallium, 6.18).

The Coligny calendar, a bronze calendar incription named for the location in France at which it was discovered at the close of the nineteenth century, reveals the nature of the Celtic year before the Celts were required to adapt to the Roman system after conquest. The bronze calendar dates from the first century BC, a victim of the Gallic War, and it is now on display at the Musée de la Civilisation Gallo-Romaine in Lyon (see: Sites and Museums in Roman Gaul: Lyon website).

The Celtic concept of the month commencing at the first quarter moon as reported by Pliny the Elder is confirmed on the Celtic calendar, since the lengths of the months and the number of months in each year show that the months correspond to lunations; and the second half of every month is headed by a label 'ATENOVX', which translates to 'returning dark'.

The evenings of the first 15 days are brightly lit by the moon: it waxes to full moon and still rises early enough to light the late evening as it begins to wane. After the last quarter, which comprises the atenoux half of the month, the moon rises after midnight and even as it passes new moon, it sets during twilight leaving the evening sky moonless, so this is the 'dark' half of the month.

Directly overhead, split into light and dark halves, the first quarter moon at sunset marked the beginning of the Celtic month. Below is a representation of the Celtic concept of the month, idealised to show 28 days by removing one each of a full and new moon image of the moon's twenty-nine and a half day lunation.

The Five Years of the Celtic Calendar

The tablet, shown in overview below, covers a period of five years. The Celtic calendar was a sophisticated system, achieving acknowledgement of both the lunar and solar cycles, a feat not effected by the Gregorian calendar in use today. The system used by the Celts had two major features: first, a semi-alternating pattern of 29 and 30 day months, reflecting the 29.5 day lunation; and second, running the calendar for a period of 62 lunations over five solar years.

Every Celtic month began at the first quarter moon, so simple inspection of the moon would immediately inform anyone when in the month any day was. Every day during the course of the month always had the same lunar phase associated with it; Atenoux commenced every last quarter - always the 16th day of the month. This standardisation of date and phase would have facilitated communication and planning.

Over the five years, in addition to the twelve regular months in each year, two intercalary months were inserted: one at the very beginning of the five years, and one in the very middle. The number of months in each year in sequence were 13, 12, 13, 12 and 12; the 5 year period was divisible by two, with each intercalary month followed by 30 regular months.

This system brought the sun and moon into close alignment at the start of every five year cycle.

The Sense of Ciallos

The name of the additional month was CIALLOS. The Gaullish word ciallos is found in the Irish and Welsh languages as ciall and pwyll, respectively, and the meaning of the word is 'sense, understanding', reflecting the 'sense' provided by their intercalation to keep the moon and sun cycles aligned.

Readers familiar with Celtic myth will recognise the Welsh word. And there are similarities of Ciallos of the calendar to Pwyll of Celtic myth.

Pwyll is the name of the Prince of Dyfed in the first branch of the Mabinogi, myths written down in the White Book of Rhydderch (in AD1325) and the Red Book of Hergest (around AD1400). The contents of these myths comprise redactions of far earlier mythological material (Jones and Jones, 1947, ix). In his myth, Pwyll meets the otherworldly Rhiannon, whose name derives from *rigantona, meaning Queen of Greatness, and they have a child born five years later, who is named Gwri Golden Hair: he was born at Calan Mai, the Celtic festival commemorating the start of summer, known as Beltaine in Ireland.

Thus, while the Ciallos months keep the five year calendar cycle aligned with the sun and the moon, Pwyll and Rhiannon meet and produce a child five years later at Calan Mai (Beltaine). In The Five Year Cycle linked feature, a five year theme found consistently across the myths of the four branches of Mabinogi is outlined. These myths were recorded from much older material, possibly maintaining a tradition of the five year periods.

A Summer start to the Year

Like the golden-haired child of Pwyll and Rhiannon, the Celtic year also began at the start of the Celtic summer. The first regular month of the Celtic year is called SAMON. The Gaullish word samon is found in the Early Irish language as samrad, which today is samhradh, and the meaning of these words is 'summer'. When the Roman calendar was introduced into Ireland, the name that was given to May was cetsoman, *cet-samhin, Cétemain, which meant 'the first weather-movement of summer' according to Cormac's Glossary (MacBain, 1982). Cormac is recorded as living until AD908, so from ancient times and consistently until today the Celtic word for the summer has remained in constant use.

The summer is marked by the festival of Beltaine. Its date on the Gregorian calendar of Rome is placed at the beginning of May; previously it will have been marked in Celtic fashion in the month for which its festival is named, the first month of Samrad, namely cetSoman, known in Gaul by the same name, Samon.

The beginning of summer has therefore been the beginning of the Celtic year since time immemorial not only in Gaul, from where the Coligny tablet was found, but across the whole Celtic world including Britain and Ireland.

Reflecting the light half of the month preceding the dark 'atenoux' half, the Celtic year was divided in two, with the light, warm summer preceding the dark, cold winter.

The second half of the Celtic year began with the month called GIAMMON. The Gaullish word giammon is found in the Old Irish as gaimred and the Old Welsh languages as gaem, and the meaning of the word is 'winter' (MacBain, 1982). The Irish word for the winter today is Geimhreadh.

The winter is marked by the festival of Samhain, named for a traditional assembly samani, as explained by Whitley Stokes, held each year at the end of the active summer half of the year (MacBain, 1982). Because of its timing, Samhain is commonly held to mean 'summer's end' (MacBain, 1982). The Samhain samani assembly is located conveniently at the beginning of November on the Gregorian calendar of Rome. When the Celtic system was in use, the assembly will have been held in the very middle of the year, in the month beginning gaimred, the winter, known in Gaul by the same name, Giammon.

The 16th Century Irish tale The Pursuit of the Giolla Dacker and his Horse reflects the persistence even to the modern era of the arrangement of the ancient Celtic year. The story begins, "One day in the beginning of summer, Finn, the son of Cumhal, the son of Trenmore O'Baskin, feasted the chief people of Erin at Allen of the broad hill-slopes. And when the feast was over, the Fena reminded him it was time to give chase through the plains and the glens and the wilderness of Erin. For this was the manner in which the Fena used to spend their time. They divided the year into two parts. During the first half, namely, from Bealtaine - the first of May - to Samhain - the first of November - they hunted each day with their dogs; and during the second half, namely from Samhain to Bealtaine, they lived in the mansions and the betas - the houses of public hospitality - of Erin; so that there was not a chief or a great lord or a keeper of a house of hospitality in the whole country that had not nine of the Fena quartered on him during the winter half of the year " (Joyce, 1907, 173).

The months comprising the two halves of the Celtic year will be looked at in detail in following two sections, Samhradh and Geimhreadh. The names of the months form complementary meaning-pairs in their respective order through the two half-years. The first months of the two halves, Samon and Giammon, form the complementary meaning-pair of summer-winter.

Five Years of the Sun and Moon

The five years shown on the bronze inscription describe a sun-moon cycle. At this level of structure, the mathematical genius of the Celtic culture comes to light. Since twelve months of the Celtic year last for (12 x 29.5 =) 354 days, the total number of days in the year do not match the solar year of 365 days. The Celtic calendar solves the problem by using the Five Year cycle, and adding an extra month of 30 days at the beginning of the first year of each cycle and in the middle of the third year of each cycle. So in Year One, an extra month occurs before Samon, and in Year Three, an extra month occurs before Giammon. The Five Year Cycle therefore comprises of the years as follows:

• Year 1: An extra month prior to Samon, then 12 months (384 days)
• Year 2: 12 months (354 days)
• Year 3: 6 months, an extra month prior to Giammon, then 6 months (384 days)
• Year 4: 12 months (354 days)
• Year 5: 12 months (354 days)

The Five Year cycle is thus divided into two 2.5-year halves, the two half cycles beginning with the extra months and each followed by 30 regular lunar months.

This Five Year cycle is very efficient in keeping the solar and lunar alignments. However, over the course of every Five Year cycle, the calendar theoretically advances by five days compared to the nominal 365 day solar year. These accumulations and comparisons can be seen in the Table below, showing the number of days elapsed over a Five Year cycle:

Year	Days	Solar year	Net difference	Cumulative difference
1	384	365	+19	+19
2	354	365	-11	+8
3	384	365	+19	+27
4	354	365	-11	+16
5	354	365	-11	+5
Totals:	1830 days	1825 days	The Calendar has progressed five days further than have the days of five solar years

The Thirty Years and Saturn

The ideal scheme presented above has a five day progression of days compared to the position of the sun. The ancient Celtic astronomers and timekeepers could solve this drift by omitting the extra Ciallos month prior to Samon every sixth cycle, so that the 5 days/cycle accumulated over six cycles, namely 30 days, were effectively removed.

Here we see the significance of the Thirty year age. Pliny recorded this age, when he speaks of the Celtic "months and years, as also of their ages, which, with them, are but thirty years" (Pliny, Natural History, 17.95) and Plutarch tells us that this occurred "at intervals of thirty years [when] the star of Cronus, which [they] call 'Night-watchman', enters the sign of the Bull, [and] those who have served the god together for the stint of thirty years are allowed to sail off home" (Plutarch, De Facie, Loeb p.185).

The following Table shows the alignment of sun and calendar over a thirty year Celtic age. The initial five year cycle does not include Ciallos in Year 1, and the 365.25 days in a solar year are accounted for. The calendar would require only three leap days over the thirty year period to provide a sun-calendar alignment. In the Table, it can be seen that the sun and calendar are in exact harmony at the completion of years 8, 16 and 24:

A lunation averages at 29.53 days, and over a Celtic age, there occur 61 + (5x62) lunations, a total of 10,955.63 days. In thirty solar years, measured as 365.2425 days each, there are a total of 10,957.275 days. That is a mere 1.645 days out of alignment.

Year	Days	Solar year	Net difference	Cumulative difference
1 Cycle 1	354	365	-11	-11
2	354	365	-11	-22
3	384	365	+19	-3
4	354	366 (leap)	-12	-15
5	354	365	-11	-26
6 Cycle 2	384	365	+19	-7
7	354	365	-11	-18
8	384	366 (leap)	+18	0
9	354	365	-11	-11
10	354	365	-11	-22
11 Cycle 3	384	365	+19	-3
12	354	366 (leap)	-12	-15
13	384	365	+19	+4
14	354	365	-11	-7
15	354	365	-11	-18
16 Cycle 4	384	366 (leap)	+18	0
17	354	365	-11	-11
18	384	365	+19	+8
19	354	365	-11	-3
20	354	366 (leap)	-12	-15
21 Cycle 5	384	365	+19	+4
22	354	365	-11	-7
23	384	365	+19	+12
24	354	366 (leap)	-12	0
25	354	365	-11	-11
26 Cycle 6	384	365	+19	+8
27	354	365	-11	-3
28	384	366 (leap)	+18	+15
29	354	365	-11	+4
30	354	365	-11	-3

The Months of the Celtic Year

The Celtic calendar is an ancient and sophisticated one. In the Celtic system, the five year calendar and the 30 year age are integral long term features that maintain the solar and lunar cycles.

The historical reports describe key attributes and the bronze tablet from Gaul attest to its usage in the first century BC. It is clear that the astronomical observations required to establish the long cyclical periods of the calendar would have occurred in the centuries before, probably about the same time as the Greek astronomer Meton, in the fifth century BC.

The thirty year age and the annual summer beginning of the year, marked by the rise of the Pleiades star cluster, provide a clue to locating a time when the Celtic system may have come into use.

There was a significant celestial event in the year 503BC, when not only did Saturn rise with Taurus at the start of the Celtic summer, but so too did Jupiter, Mars, Venus and Mercury, shown in the previous section looking at the Pleiades Cycle.

In the following two sections, Samhradh and Geimhreadh, the names of the months of the year are examined.

| Introduction | The Pleiades Cycle | The Coligny Tablet | Samhradh | Geimhreadh |
| Celtic Calendar 2008 | The Southern Seasons Celtic Calendar 2008 | Celtic Calendar Forum |

References for this section.

ancient sources

C. Julius Caesar. Caesar's Gallic War. Translator. W. A. McDevitte. Translator. W. S. Bohn. 1st Edition. New York. Harper & Brothers. 1869. Harper's New Classical Library. [available on-line:
http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Caes.+Gal.+6.18 ]

Pliny the Elder. The Natural History. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855. [available on-line:
'Historical Facts Connected With The Mistletoe': http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+17.95]

Plutarch, Life of Caesar. In: Plutarch. Fall of the Roman Republic. Transl. R. Warner (1972). London: Penguin, pp. 243-310.

Plutarch. Moralia. De Facie 'The Face in the Moon' with an introduction. Vol. XII of the Loeb Classical Library edition, 1957. [available on-line:
http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/
Moralia/The_Face_in_the_Moon*/Introduction.html ]

websites and image credits

'Cernunnos' image: http://www.kernunnos.com/deities/cernunnos/ see also:Nationalmuseet - The National Museum of Denmark: Celtic cult object found at Gundestrup. Dated about 100 B.C. http://www.natmus.dk/sw33830.asp

'Coligny Tablet' image: http://www.geocities.com/astrologyzodiacs/celticzodiac.htm
see also: http://www.answers.com/topic/coligny-calendar

Cormac's Glossary, translated and annotated by John O'Donovan, edited with notes and indices, edited by Dr. Whitely Stokes, published in 1862 and 1868 Calcutta. Llanerch Press; Facsimile edition (Mar 2000)
A useful on-line resource for Whitley Stokes: http://www.ucc.ie/celt/stokebib.html

MacBain, A. (1982) An Etymological Dictionary of the Gaelic Language
http://www.ceantar.org/Dicts/MB2/index.html

'Moon phase' animated gif and series images: Virtual Reality Moon Phase Pictures
http://tycho.usno.navy.mil/vphase.html

'Moon occultation with the Pleiades cluster 2006' imagehttp://www.skynightly.com/reports/Moon_To_Sweep_Through_The_Pleiades.html

'Saturn occultation with the Moon' image: http://apod.nasa.gov/apod/image/0202/occsat_martinez_full.jpg

Sites and Museums in Roman Gaul: Lyon http://www.athenapub.com/rhone6.htm

'Sun, moon, first-quarter' image: http://abyss.uoregon.edu/~js/cosmo/lectures/lec03.html

The Mabinogion (1947) translated by Gwyn Jones and Thomas Jones, Everyman, London.

The Pursuit of the Giolla Dacker and His Horse, an Irish story known from the 16th century. In: Old Celtic Romances, collected by PW Joyce (1907: republished 2000) Wordsworth Editions Ltd in association with FLS Books, The Folklore Society.

Other 'Coligny Calendar' websites

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