I. The Preface (signed by Cajetanus Amatus) to the Index of Benedict 1758 II. The Address to the Reader, signed by Saccheri III. The Ten Rules of the Index of Pius IV (Trent) 1564 IV. Observations on the Rules, from the Index of Clement VIII 1585 V. Observations on the Rules from the Index of Alexander VII 1664 VI. The Instruction of Clement VIII VII. The Constitution of Benedict XIV VIII. The Decree _de libris prohibitis_, from the Index of Benedict 1758 IX. The _Mandatum_ from the Index of Leo XII 1825 X. The _Monitum_ of the Congregation of the Index 1828 XI. The _Monitum_ of the Congregation of the Index 1836 XII. The Constitution of Pius IX 1869 XIII. The Declaration of Pius IX (in regard to the dogma of the Immaculate Conception) 1854 The Index of 1900 is very attractively printed, and is a credit to the work of the papal printing-office. It is the first of the Roman issues that can be so described. This second Index repeats, with a few omissions, the lists of the volumes of 1896, with the addition of certain titles selected from the publications of the intervening four years. The prefatory matter of the volume of 1900 is made up as follows: I. The Papal Brief, which bears the signature of Cardinal Macchi. II. A Preface, with the signature of Esser, Secretary to the Congregation. III. The Constitution of Leo XII. IV. The _Decreta Generalia_. V. The Constitution of Benedict. I have thought it in order to present the full text of the first four of these documents as fairly representative of the literary policy of the Church at the close of the 19th century. BRIEF OF LEO XIII