This subject is one of the aspects of a historiographical and anthropologic study that, over the years, has resulted in monographic articles along with a volume dedicated to Celtic ethnography in Posidonius of Apamea. Posidonio d'Apamea e I Celti. Un viaggiatore Greco in Gallia prima di Cesare, Roma, Aracne Editrice, 2011, pp. 508.
As it is known, the comparison between the descriptions of continental Celts contained in the pages of the Greek scientist and philosopher and the customs described in some traditional Gaelic (insular Celtic) sagas, was the subject of a lively cultural debate. I intend to give my contribution as a scholar of classic antiquity (namely a Hellenist) that confronts with the Celtic world of which is no specialist, thus knowingly facing all the subsequent risks.
The polymath of Hellenistic age Posidonius of Apamea (135-50 B.C.) represents the most important ancient Greek source about the knowledge of Celtic continental world. He was an invaluable direct eye-witness of the Celtic customs and his observations, handed down by Athenaeus (Deipnosofisti, IV 151e-152f and 154a-c, VI 246c-d), Diodorus in his Biblioteca Historica (V 25-32) and Strabo in IV 4, 1-4 in Geography are about banquets, feasts, description of clan leaders, warriors and military and country servants, duel fightings, weapons, anthropological ethnic nature of Celtic people and the religion of druidism. Posidonius, even though carrying out research into Celtic ethnography, compares Celtic customs to behaviour of heroes of Greek epic tradition.
Anyway if we read Posidonius' descriptions we can find a deep analogy with various aspects of Celtic society of sagas of Gaelic Middle-Age tradition, particularly of some famous Irish sagas from Ulster: first of all, Fled Bricrenn and then Scéla Muicce Meic Da Thó. This comparison between legendary stories written in XII century in Ireland and the descriptions of Greek writer shows that Posidonius was a trustworthy writer in his ethnographical report of the Celts. In many cases this correspondance about Celtic world is really astonishing. In conclusion, Celtic archaeology (insular and continental) confirmed Posidonius' reliability about ancient Celts, too.
During the banquet the warriors of Fled Bricrenn (and Scéla Muicce Meic Da Thó saga, too) are sitting in a circle around a table voraciously eating meat (mainly pork), cutting the meat with a knife (a Scottish dirk) and drinking a lot (100a). The banquet is attended by armed men to defend the chief and a precise hierarchy of seats exists based on the social rank (100b and 101a). Both Bricriu, and Meic Da Thó prepare a great banquet to which many warriors are invited with the aim of making them fight one against the other at the moment of the choice for the award of the champion's share, the curad-mir (100b, 101a, 104a). Meic Da Thó also invites rival clans hoping that they challenge each other to obtain the privilege of the pork that gives the name to the saga, while Bricriu mischievously promises the champion's share to each of the three heroes of the invited tribes urging them to claim it during the feast. The first part of the story in Fled Bricrenn is dedicated to the description of the banquet hall whose preparation took a whole year, like Luvernius'banquet, the richness of Briucrui's house, a building made just for the event, and the opulence of the banquet (99b), then a section presents the curad-mir and the pure wine (100b), describing the beginning of the first quarrels between the invited champions (101a): at first simple arguments degenerating in true physical clashes and fights like the monomachiai by Posidonius (101a). In Fled Bricrenn the brawl is quelled by the intervention of king Conchobar and the druid Sencha that pull the contenders apart and make them sit again in a circle around the fire. The story of Fled Bricrenn ends after violent fights and the section dedicated to fight against the Giant (many passages are about hunting and cutting heads of enemies killed in battle, like 102b, 105a) with the victory of the most valorous hero, the kratistos, Cu Chulainn, in obedience to the code of honour the social prestige is based on.
Quotations from Fled Bricrenn in Lebor na hUidre, ed. R.I Best, O. Bergin, Dublin, 1929, 3rd reprint 1992 (LU 99b-112b 48).
15th International Congress of Celtic Studies 13-17 July 2015, University of Glasgow.