Of the literature of pagan Ireland, though much has come down to us, we have only a very small fraction of what once existed, and what we have has been transmitted and modified by persons of later times and different culture, who, both consciously and unconsciously, have changed it, so that it is very different from what it was in its original form; but the subject and the main outlines still remain, and we have many accounts of both voyages and underground journeys to the other world. The oldest voyage is, perhaps, that of Maelduin, which, Tennyson has transmuted into English under the title _The Voyage of Maeldune_. This is a voyage undertaken for revenge; but vengeance, as Sir Walter Scott has pointed out in his preface to _The Two Drovers_, springs in a barbarous society from a passion for justice; and it is this instinct for justice that inspires the Irish hero to endure and to achieve what he does. Christianity has preserved this legend and added to it its own peculiar quality of mercy; and this illustrates one of the characteristics of Ireland's pagan literature--it is imperfectly Christian and can readily be made to express the Christian point of view. Another voyage of pagan Irish literature is the _Voyage of Bran_. In this tale idealism is the inspiration that leads the hero into the unknown world. A woman appears who is invisible to all but Bran, and whose song of the beauteous supernatural land beyond the wave is heard by none but him; so that, after refusing to go with her the first time she appears, at length he steps into her boat of glass and sails away to view the wonders and taste the joys of the other world. In these tales we have two main elements, one real and one ideal. The real element is the fact that the ancient Irish unquestionably made voyages and visited lands which the fervid Celtic imagination and the lapse of time transformed into the wonderful regions of the legends. The stories are thus early geographies, and they show unmistakably a knowledge of western Europe and of the Canary Islands or some other tropical regions; perhaps also, some have gone so far as to claim, they are reminiscent of voyages to America.