I. The first and immediate influence was doubtless to arrest its progress. After ages of apparent barrenness, the genius of the Gaelic-speaking peoples had at length produced the germ of a literature which in the days of St Patrick and St. Columba took root and began to grow. For well-nigh four centuries it had gone on developing in a most promising way. The quiet and leisure of the monasteries furnished the atmosphere most suitable for its inception and subsequent growth. These religious retreats were then the centres of learning and nurseries of thought, and many men were arising within their sacred walls who had a genuine love and taste for writing—a love so great that they were not merely content with copying books, composing poems, or writing history, but they embellished them in a way which has excited the admiration of modern times. Gaelic literature both in Ireland and Scotland was thus bidding fair to yield a rich and abundant harvest when the blight of the Norse invasion fell suddenly upon it, and effectually hindered its farther advance for several centuries. The history of literary work in every age and country shows that it is mostly in times of peace that this delicate plant flourishes. In the stormier periods, when wars are waged, changes frequent, and a spirit of unrest abroad, production of books is rare or even non-existent. When the Celts themselves were a warrior race, living for the most part by the sword, and migrating from land to land, they had no literature that we know of. The conditions of life were not such that men could quietly cultivate the art and practice of writing. Life was too full of change, too turbulent, and too uncertain. Similarly the Norsemen during the Viking age, till they gained a peaceful retreat in Iceland, were no litterateurs. Sailing and fighting were more exciting, and with these the habits of the scribe or of the author were not entirely compatible. And so when the tide of invasion burst upon the monasteries of Ireland and Scotland, when rest from strife and security from change could no longer be had, authorship, if it did not entirely cease, became more rare and spasmodic. This is particularly true of Scotland, for with the exception of the Book of Deer, with its Latin contents of the ninth century, and its Gaelic entries written towards the end of the Viking period, we have nothing to show, of known Scottish origin, from the beginning to the end of these incursions. Ireland was more fortunate in that in spite of invasion her literary output was more continuous, especially in the department of poetry.