Section — Prümmer, Manuale Theologiae Moralis
§ 3. On the reading of heretical books
530. Already for centuries79 the Church with watchful vigilance has proscribed bad books and forbidden the reading of them under grave penalties. There will be speech below about those ecclesiastical penalties in the treatise on censures. Almost nothing is so pestiferous for true religion and good morals as the reading of bad books. Hence Leo XIII says: "In the struggle [against the doctrine of Christ] the wiles and arts of harming of the enemies are indeed various and innumerable; but among the first is the full-of-dangers intemperance of writing and disseminating among the people the things which have been written badly. For nothing more pernicious can be thought of for staining souls through contempt of religion and through the many allurements of sinning."80 The same Pontiff established certain new general rules for discerning the categories of prohibited books. These rules indeed are renewed in the Code of Canon Law c. 1399. Thus are prohibited, e.g.: "Books of any writers whatsoever defending heresy or schism, or in any way overthrowing the foundations of religion itself; books which deliberately attack religion or good morals; books of any non-Catholics whatsoever which professedly treat of religion, unless it is certain that nothing against the Catholic faith is contained in them; ... books which establish as licit duel, suicide, or divorce, which treat of Masonic sects or other societies of the same kind and contend that they are useful and not pernicious to the Church and civil society; books which professedly treat, narrate, or teach lascivious or obscene matters." - All these books are prohibited on account of the imminent danger to faith and good morals. But if in a particular case for an individual man such danger does not exist on account of the firmness of his character, nevertheless the law of prohibition perseveres.81 But then the faculty of reading prohibited books is easily obtained from the competent authority, if a reasonable cause exists.
Note. No more efficacious way is given of preventing the reading of bad books and papers than to provide good books for the people to read, and especially good daily or periodical papers. Hence with the best fruit in diverse regions associations operate for spreading good books.82
79 On the history of the prohibition of books, see Jos. Hilgers, Der Index der verbotenen Bucher (Freiburg, 1904), 2 sqq., Geschichtl. Uberblick des kirchl. Bucherverbotes.
80 Const. "Officiorum et munerum," January 25, 1897.
81 Compare what was said above (n. 218) about law founded on the presumption of common danger.
82 E.g. in Germany: the Borromaeusverein; in other regions: l'oeuvre de la bonne presse.