But Ireland was exempt from the sweeping changes brought about through long periods of Roman and Saxon occupation; no great upheaval from without disturbed the native political and social conditions up to the coming of the Norse and Danes about the beginning of the ninth century. Agricola, standing on the western coast of Britain, looked across the dividing channel, and reflected upon "the beneficial connection that the conquest of Ireland would have formed between the most powerful parts of the Roman Empire," but, fortunately for the literature of Ireland, if not for her history, he never came. The early incursions of the Scotti or Irish were eastward into England, Wales, and Gaul, and there seem to have been few return movements towards the west. Ireland pursued her path of native development undisturbed. It is to this circumstance that she owes the preservation of so much of her native literature, a great body of material, historical, religious, poetic, romantic, showing marks of having originated at a very early time, and of great variety and interest. At what period this literature first began to be written down we do not know. Orosius tells us that a traveler named Aethicus spent a considerable time in Ireland early in the fifth century "examining their volumes", which tends to prove that there was writing in Ireland before St. Patrick. But the native bard must have made writing superfluous. The man who could, at a moment's notice, recite any one out of the 350 stories which might be called for, besides poetry, genealogies, and tribal records, was worth many books. Only a few were expert enough to read his writings, but all could enjoy his tales. The earliest written records that we have now existing date from the seventh or eighth century; but undoubtedly there is preserved for us, in these materials, a picture of social conditions going back to the very beginning of our era, and coeval with the stage of civilization known in archaeology as _La Tène_ or "Late Celtic". To help his memory the early "shanachie" or story-teller grouped his romantic story-store under different heads, such as "Táins" or Cattle-spoils, Feasts, Elopements, Sieges, Battles, Destructions, Tragical Deaths; but it is easier for us now to group them in another way, and to class together the series of tales referring to the Tuatha De Danann or ancient deities, those belonging to the Red Branch cycle of King Conchobar and Cuchulainn, those relating to Finn, and the Legends of the Kings. The hundred or more tales belonging to the second group are especially valuable for social history on account of the detailed descriptions they give of customs, dress, weapons, habits of life, and ethical ideas. To the historian, folklorist, and student of primitive civilizations they are documents of the highest importance.