The Leonine Index repeats but two prohibitions back of the date of 1600. The first, bearing date 1575, makes entry of the title of the _Chronicon_ of Conrad of Lichtenau, and the second, under the date of 1580, the title of _Il Salmista secondo la Bibbia_, etc. During the above specified period, covering three centuries, the lists comprise some four thousand titles, but this number includes a hundred and eight authors whose entire writings (under the entry of _Opera omnia_) came under condemnation. If the works of these writers were added separately to the schedule, the titles would aggregate about five thousand. Of these titles, some fifteen hundred belong to the 17th century, twelve hundred to the 18th, and thirteen hundred to the 19th; while from the publications of the last decade of the 19th have been selected but one hundred and thirty-one titles. This last group includes, however, the _Opera omnia_ of Zola. The writers of the 19th century who have been distinguished through the condemnation of their entire works comprise the following: Sue, 1852; Dumas (father and son), 1863; Sand (Dudévant), 1863; Balzac, 1864; Champfleury (Fleury-Husson), 1864; Feydeau, 1864; Murger, 1864; Soulié, 1864; Hume (David), 1827; Morado, 1821; Plancy, 1827; Proudhon, 1852; Spaventa, 1856; Vira, 1876; Ferrari, 1879; Zola, 1895. The omission from the Leonine Index of a long list of names, which appeared in earlier Indexes connected with the term _Opera omnia_, is to be understood as giving permission to the faithful for the use of such books of these writers as do not appear under specific condemnation or as cannot at once be classed under the general prohibitions. All of the books of writers of this first class which do not antagonise either the true Faith or good morality are now free for Catholic readers. This exception would of course continue to rule out the writings of the leaders of the original Reformation, Luther, Calvin, Melanchthon, and the rest, although the names of these writers do not find place in the Leonine lists. The Index of Benedict (who from the liberal character of his convictions and policy was sometimes spoken of as the free-thinking Pope) strengthened the prohibitions against some fifty authors. The names of these authors, which had previously been connected only with specific books, are entered in the Index of 1758 with _Opera omnia_. Hilgers emphasises the greater liberality of Leo XIII in recalling these authors from the _Opera omnia_ classification and in leaving condemned only certain specific works. He gives as another example of the liberality of Leo the freeing from condemnation of the famous treatise by Grotius, _De Jure Belli ac Pacis_. This had previously been condemned with a _d.c._ but the objectionable portions had never been specified and no corrected edition had ever been attempted. Another work of this class, previously condemned but now left free by Leo, is the _Paradise Lost_ of