Herein lies a strange trait of Celtic life, that the great literary revivals should be thus simultaneous, and common to all the sundered groups, though these latter are isolated so much linguistically and locally. Not once or twice in their history has this curious affinity of genius and sentiment been evinced. In the case of the Gael, no sooner was the grip of the Vikings relaxed than the bards and schools began to flourish again. The new Irish king, the semi-usurper Brian Boru, helped much towards this happy consummation, as he was a real patron of letters and worked hard to restore the fallen fortunes of Gaelic literature. Early in the eleventh century he was on the throne, and that and the following century witnessed the new and copious revival of art and learning. To this period belong the great monuments, such as the Leabhar Na h’Uidhre, the Book of Hymns, the Book of Leinster, as well as the Scottish Book of Deer. During these two centuries a host of poets and some annalists lived, the chief of whom were Flann of Monasterboice and Tighernach. Quite a number of the names of prominent bards who wrote then are given by Dr. Hyde in his _Literary History of Ireland_. And we know that from this time the interest taken in the past gave rise to that rich and abundant medieval succession of books of saga common to Ireland and Scotland. But though these latter were compiled, some of them after the twelfth century, the actual revival did not last beyond the Norman Conquest of Ireland, which culminated at the close of that same twelfth century, arresting Irish development and disintegrating Irish life. So that for 300 years after, Erin produced nothing comparable to her former achievements. Turning to the Cymri, on the other hand, we find the remarkable intellectual awakening of the eleventh and twelfth centuries ushered in in a similar way as in Ireland, by the advent of new rulers. Rhys ap Tewdwr, who had taken refuge in Brittany, returned in 1077 and ascended the throne of South Wales, to which he laid claim as true heir. And Gruffyd ap Kynan, similarly exiled in Ireland, came back to reign in North Wales in 1080. Uniting their forces in one first great attempt, these two hereditary princes overthrew the reigning monarch, and were confirmed on the thrones of their ancestors. Like Brian in Ireland, they also in their own fatherland were instrumental in introducing a new era of literature. In North Wales it showed itself in a revival of poetry, while in South Wales it took the form of prose. Thomas Stephens mentions no less than seventy-nine bards who lived between 1080 and 1400, many of whose pieces are still extant in MSS.