In February, 1778, Pius VI issues a general prohibition as follows: _Libri omnes incredulorum, sive anonymi sive contra, in quibus contra religionem agitur_. This prohibition, instead of being included in the _Decreta Generalia_, where similar decrees had heretofore been printed, is placed under the term _libri_. Connected with the decree, is the specification that the permission to read books of this class can be granted only by the pope himself. It is probable that this general prohibition did not prove particularly effective, as it was hardly possible for the average reader to be able at once to identify a work as irreligious in tendency or to have knowledge by name of all of the writers who were to be classed as unbelievers. The difficulty was naturally greater in the case of anonymous works. In the Spanish Indexes of 1747 and 1790, the editors have indicated by a mark the books the reading of which is prohibited even to those who have secured permission for the use of works included in the general Index lists. There was published in Paris an encyclopaedia under the title _l’Encyclopédie ou Dictionnaire raisonnée des Sciences, des Arts, et des Métiers, par la Société des Gens de Lettres_. It bore the names, as editors, of Diderot and d’Alembert. In 1759, at the time of the prohibition, seven volumes only had been published. The first two volumes, printed in 1751, had been condemned in 1752, under an order of the Council of the King; but two years later, the king issued a privilege for the continuation of the work. The papal brief states that the volumes first issued had been condemned and that the later issues, described as a revised edition, had been carefully examined by the Inquisition and again condemned on the ground that the teachings and propositions contained in them were false and pernicious and tended to the destruction of morality; and further that these teachings promoted godlessness and the undermining of religion. In 1759, the royal privilege under which the publication was being continued, was withdrawn. The editors and printers succeeded, however, in carrying on the work without coming into open conflict with the authorities, and by 1772, twenty-eight volumes had come into print. In April, 1757, a decree of Louis XV prohibits, under penalty of death, the production and distribution of any writings against religion. There does not appear, however, to be on record any instance of the carrying out of this penalty. The papal brief issued in 1759 in regard to the treatise of Helvétius, _De l’Esprit_, describes the book as “antagonistic to the Christian religion and to natural morality, and as maintaining the pernicious and damnable views of the Materialists and of the Epicureans,” and further, “as maintaining many godless and heretical propositions.”