In Irish legend Ogma, one of the Tuatha De Danann who was skilled in dialects and poetry, seems to be credited with the invention of the Ogam alphabet, and he probably was the equivalent of the Gaulish god Ogmios, the god of eloquence, so interestingly described by Lucian.
We may take it then that the Irish pagans knew sufficient letters to hand down to Irish Christians the substance of their pagan epics, sagas, and poems. We may take it for granted also that the greater Irish epics (purely pagan in character, utterly untouched in substance by that Christianity which so early conquered the country) really represent the thoughts, manners, feelings, and customs of pagan Ireland.
The effect of this conclusion must be startling indeed to those who know the ancient world only through the medium of Greek and Roman literature. To the Greek and to his admiring master, the Roman, all outside races were simply barbarians, at once despised, misinterpreted, and misunderstood.
We have no possible means of reconstructing the ancient world as it was lived in by the ancestors of some of the leading races in Europe, the Gauls, Spaniards, Britons, and the people of all those countries which trace themselves back to a Celtic ancestry, because these races have left no literature or records behind them, and the Greeks and Romans, who tell us about them, saw everything through the false medium of their own prejudices. But now since the discovery and publication of the Irish sagas and epics, the descendants of these great races no longer find it necessary to view their own past through the colored and distorting glasses of the Greek or the Roman, since there has now opened for them, where they least expected to find it, a window through which they can look steadily at the life of their race, or of one of its leading offshoots, in one of its strongholds, and reconstruct for themselves with tolerable accuracy the life of their own ancestors. It is impossible to overrate the importance of this for the history of Europe, because neither Teutons nor Slavs have preserved pictures of their own heroic past, dating from pagan times. It is only the Celts, and of these the Irish, who have handed down such pictures drawn with all the fond intimacy of romance, and descriptions which exhibit the life of western Europeans at an even earlier culture-stage in the evolution of humanity than do the poems of Homer.