The author of this Manual, while calling it a History of the Roman Breviary, has been far from supposing that so great a subject could be exhaustively treated in so few pages. His object has been to summarise, and on some points to state more precisely, and with all possible clearness, the results reached or led up to by such learned writers as Cardinal Bona, Cardinal Tommasi, Thomassin, Dom Gueranger, and Monsignor de Roskovany. In summarising these results, he has in every case verified them by reference to their original sources, being determined that, though his work was to popularise the subject, it should be work at first hand, and give direct information. He has even been led to revise them, not considering himself forbidden to make researches on his own account, to classify in accordance with his personal observation, and to draw conclusions on his own responsibility and at his own risk. But in thus treating this vast subject it has not been possible for him to avoid seeing how many unexplored countries are still to be found in that ancient continent. We are still without a critical edition of the Liber Responsalis of the Roman Church; we have no collection or scientific classification of the most ancient Ordines Romani; no catalogue of.the Roman liturgical books from the eighth to the thirteenth century; no catalogue or classification of monastic breviaries of dates anterior to the thirteenth century, or of breviaries, whether Roman or non-Roman, from the thirteenth to the fifteenth century; we have not even a descriptive account of printed Roman breviaries' Not to speak of documents which might be published relating to the various reforms of the Roman Breviary in the sixteenth, seventeenth, and eighteenth centuries. A man might gladly devote years to such researches, but then, the book we would write would not be a Manual: a collection such as the Analecta Liturgica of Mr. Weale would be none too large. So one must needs restrain oneself, and be content simply to strive to keep in the right track, and guide others along it. The author has endeavoured to avoid those practical questions of ritual which depend either on moral theology or on the decisions of the Congregation of Rites; and still more to keep clear of the prejudices which, in France at least, have too long embittered such questions. His aim has been to treat the subject from the standpoint of Christian archaeology and the history of Christian literature. More fortunate than some liturgical writers of the last generation, we are now able to speak of liturgy, without being influenced by external considerations; we can criticise and we can admire without reference to any other matter; taking for the guiding principle of our appreciation those admirable words, worthy of S. Gregory, though they are not his, non pro locis res, sed pro rebus loca nobis amanda sunt. Newman, while still an Anglican, could write this remarkable passage: "There is so much of excellence and beauty in the services of the Breviary, that, were it skilfully set before the Protestant by Roman controversialists al the book of devotions received in their Communion, it would undoubtedly raise & prejudice in their favour, if he were ignorant of the circumstances of the case, and but ordinarily candid and unprejudiced." It is this excellence and beauty of the Roman office which I have endeavoured to express, just as I have myself been sensible of it. And as to the circumstances of the case, alluded to by Newman, I have considered it my duty to analyse them just as they are, without attempting to minimise them, being well convinced that they would not tend to diminish the genera. Impression of esteem and admiration wbich the Roman Breviary must produce, whether considered as regards its contents or the sources from Which they are drawn.