Before entering upon his subject, Dr. Reeves sets forth the object he has in view, and the method by aid of which he proposes to attain it. Persuaded that indulgence in speculation has brought great detriment to the cause of Irish history and antiquities, he puts forward in these pages "not so much his own views on the subject, as a comprehensive statement of trustworthy materials upon which to form a sound and philosophical opinion". With this object in view, but one method was open to him, namely, to collect and arrange all the scattered evidence upon the subject which his thorough and varied acquaintance with Irish, Scotch, and English materials of history, both published and unpublished, enabled him to accumulate. This he has done with fulness and precision, and having completed his task, he leaves it to the impartial reader to combine the details placed before him, and draw his conclusions for himself. Of this impartiality the author believes that he sets an example in his own proper person; whatever his private sentiments may be on the points at issue, he professes to hold them back. Not that he is cold or indifferent to his subject, for he declares that there is "one weakness, if it be a weakness, to which he must plead guilty, and that is, earnestness in the cause of Ireland's ancient dignity". By that earnestness we are all gainers, and the labours it has dictated to the author will always hold a high place in Irish literature. The work consists of four parts, with a valuable appendix. The first part contains preliminary observations, and is divided into two sections--one on the origin of the name Céle-dé, or Culdee, the other being devoted to an analysis of that name. Part II. is entitled "_The Céle-dé in Ireland_", and consists of ten sections, respectively treating of strangers in Ireland called Céle-dé, of the Céle-dé of Tallaght, of Armagh, of Clonmacnoise, of Clondalkin, of Monaincha, of Devenish, of Clones, of Pubble, and of Scattery Island. Part III. is headed "_The Céle-dé or Kelidei of Scotland_", and has fourteen sections, the first being occupied with general remarks, the others with the Kelidei of St. Andrew's, of Dunkeld, of Brechin, of Rosemarkie, of Dunblane, of Dornoch, of Lismore, of Hy, of Lochleven, of Abernethy, of Monymusk, of Muthill, and of Monifreth. Part IV., on the _Colidei of England and Wales_, has two sections--one on the Colidei of York, the other on the Colidei of Bardsey. The appendix consists of evidences from authorities referred to in the essay, and constitutes a valuable collection of documents, the importance of some of which extends far beyond the question which they are here intended to illustrate.