Adamnan’s best known book is essentially a Life of St. Columba, written not in any chronological order, but on a characteristic plan of his own. There are two prefaces, and what would really be the gist and subject-matter of a modern biography is condensed by him into one short paragraph at the end of the second of these. The work is then divided into three parts or books. The first deals with prophetical revelations, the second with miracles, the third with visions of angels; and under these titles he groups all the most striking stories of the saint’s life. All the collateral information—and it is not much—regarding the history of the time, the social life, the manners, customs, language, topography, etc., we get merely by the way in the telling of the tale. Adamnan apparently had no thought that his readers would wish to know something of these, or if he had he did not deem it any part of his task to enlighten them. He was writing for his own times, and he could not conceive that the eye of any monk or other reader could wander off from the central luminary to mere details of the environment. It is at once the limitation and strength of the enthusiast and the specialist. How could he know that he was writing for the far-distant future?—this unassuming monk in his cell, unconsciously addressing a people who have emerged from his theory of the universe, and who listen and wonder at his stories, which to them have all the charm and interest of fairy tales. _Tempora mutantur, eheu!_ The little facts that incidentally dropped from his pen are those most sought and valued now, while the miracles, visions, and prophecies which he took to be the soul and substance of the book, wear a different aspect to modern eyes. It is these trifling details, sometimes mere names, that give us glimpses into the state of society in Ireland and Pictland, and into the civil and ecclesiastical history of the time.