_Index librorum prohibitorum, Leonis XIII Sum. Pont. auctoritate recognitus SS. D. N. Pii P. X iussu editus. Præmittuntur Constitutiones Apostolicæ de examine et prohibitione librorum._ (Index of forbidden books, revised by the authority of Pope Leo XIII, and issued by order of His Holiness Pope Pius X. Preceded by the Apostolic Constitutions on the examination and prohibition of books.) A glance at the neatly printed volume will disclose the reason why it is called “Index”;—almost nine-tenths of it consists of a catalogue of books condemned by the Roman authorities. Of still greater importance than this catalogue are the first thirty-four pages, which give, in the “Apostolic Constitutions,” the general laws of the Church regarding books. There are only two “Constitutions.” But the whole work is introduced by a brief of Leo XIII, in which the Pontiff declares that this edition is to be the authentic one for the whole Church. _It is to be binding on all the faithful of the universe, regardless of race or language, nationality or country, education, learning or station in life._ In a preface headed “Lectori S.,” the Secretary of the Roman “Congregatio Indicis” compares this edition of the “Index” with the former ones, points out the changes that were made, and explains the technical arrangement of the book. After these preliminaries follow the “Constitutions.” The first is the “Officiorum ac munerum” of Leo XIII, dated Jan. 25, 1896. This document recasts the whole legislation of the Church regarding the production, dissemination, reprinting and prohibition of such books as the Church may and must concern herself with. It abrogates all former laws and regulations of General Councils as well as of Sovereign Pontiffs, with one exception: the Constitution Sollicita ac provida of Benedict XIV, also reprinted here, by which this great pope established or rather sanctioned a method—the one still in use—of examining and passing sentence on the books submitted to the Roman authorities. These two Constitutions contain the entire general legislation of the Church on the head of books. There is no “Index expurgatorius.” If there were, it would consist of books condemned conditionally, _donec corrigatur_, “until amended.” But such books are all entered in the ordinary Index, with those two Latin words added. In Pope Leo’s edition they are, besides, marked with an asterisk. 2. The Power of the Church. That the Church has the right to legislate on the publication and use of all books that touch on questions of faith and morals, must be evident to every Catholic. It is a truth clearly contained in the words of Christ to St. Peter: “Feed my lambs, feed my sheep,” and in the duty imposed on the Apostles of “teaching the faithful to observe all, whatsoever I have commanded you.”