The _Commedia_ is like a mighty river formed by the confluence of several great tributaries, each of which is fed by innumerable springs and streamlets, which have their rise in regions remote and most diverse from each other, and are all tinged by the soil of the lands through which they flow. It is with one of these tributary streams that the following pages deal, and that not the least important among them, for to it the Vision of the Otherworld, as current in the later Middle Ages, owed much both of its popularity and its contents, not, indeed, by way of direct derivation or suggestion--a view which several circumstances forbid us to entertain--but as the result of an influence which, in an earlier stage of culture, had determined the direction which the Vision legend actually followed in its later developments. The subject would appear to have possessed a special fascination for the Irish writers at the time when Ireland was the chief intellectual centre of Western Europe, and the constant flux and reflux of Irish teachers and foreign students necessarily tended to spread abroad so much, at any rate, of the compositions of the Irish schools as was in harmony with the tastes and beliefs of Christendom at large. By far the most important of the Apocalyptic writings which proceeded from the Irish schools is the Vision which bears the name of St. Adamnán, of which a translation is given in the present volume. It is interesting to compare it with the later and greater work, and to mark the numerous points of resemblance which may be discerned in works so widely different. This and the like productions of a ruder, but not ignorant nor uncultured, age, deserve no less attention than that which we bestow upon the works of the primitive schools of art and letters, before Giotto and his compeers had effected the release of painting from the bonds of formalism, and had opened out the ways of Nature and imagination, and before the immediate predecessors of Dante had rendered possible his _dolce stil nuovo_. At the same time it may be seen how the legend which received its apotheosis in Dante’s immortal verse came into being upon the misty heights of primitive myth, and after forming the theme of poets and philosophers in classical antiquity, entered into the literature and teaching of the early Christian Church; how the ecclesiastical legend, as it had now become, was adopted into the Irish Church at the time of its greatest activity, and there received the impress of the national genius, and became blended with the national traditions; thence it returned again to become a part of the general literature of Europe, and received yet further elements from the newly popular romances of chivalry, and still more from the revived classical tradition, until the elixir of the great magician’s genius finally transmuted the amalgam into gold to be a κτῆμα ἐς ἀεί.