Are Catholics allowed to read and/or own books that attack Catholicism or argue in favor of other religions without permission, even if it is for a legitimate reason like strengthening their faith? I was reading an old moral theology book but I'm not sure exactly what it meant and if it was just talking about books that were on the Index of Forbidden Books. For example, a quote from John McHugh and Charles J. Callan, OP's *Moral Theology* (1929) [§849-§866. Dangerous Reading](https://archive.org/details/moraltheology0001john/page/320/mode/2up) : > **849. Dangerous Reading.**—There is a threefold prohibition against the reading of literature dangerous to faith. > > - (a) The *natural law forbids* one to read or hear read written matter of any description which one knows is dangerous to one’s faith, even though it is not dangerous to others and not forbidden by the law of the Church. For a similar reason one may not keep such material in one’s possession. Example: Titus and Balbus read the letters of a friend on Evolution. Titus finds nothing unsound in the letters, and is not troubled by reading them; but they fill the mind of Balbus with doubts and perplexities, as the subject is above him. This reading is naturally dangerous for Balbus, but not for Titus. > >- (b) The *law of the Church forbids* the use of certain kinds of writings or representations dangerous to faith (Canon 1399), as well as of those *individual* writings that have been denounced to the Holy See and placed on the Index, or forbidden by other ecclesiastical authorities. > >- (c) The law of the Church also *pronounces ipso facto excommunication* against those who make use of works written by unbelievers in favor of their errors (Canon 2318). > > [... omitted: the rest of the "Dangerous Reading" section (§850 to §866) which covers in great detail every aspect and every term mentioned in §849, such as §862 that spells out what "use" exactly means in §849c]

According to [*Index of Prohibited Books*](https://en.wikipedia.org/wiki/List_of_authors_and_works_on_the_Index_Librorum_Prohibitorum) , all of the works of Thomas Hobbes were placed on the Index of Prohibited Books in the year 1649. Thomas Hobbes wrote many more books after 1649, including his magum opos, *Leviathan,* which was published in 1651. (Hobbes died in 1679.) QUESTION: Does the aforementioned list really contain *all* of the works of Hobbes, or just those, perhaps, that were published by 1649? Is it possible that when the list displayed by the above Wiki link indicates "all books," it really means the author himself; e.g., *David Hume* who died after the year of of his books were banned? In the case of Hobbes, I am most interested in determining whether or not his *Leviathan* was actually banned. Thank you.

The Wikipedia page for Blaise Pascal's apologetic work *Pensées* says that the Catholic Church banned the book: > However as conflicting with the orthodoxy of the Catholic Church it has been forbidden to print or read by the Index Librorum Prohibitorum. Source: [Pensées - Wikipedia](https://en.wikipedia.org/wiki/Pens%C3%A9es) Following Wikipedia's citations, [Beacon for Freedom of Expression](https://beta.nb.no/extrip/beacon/9800645) says the book was banned for religious reasons in 1789, but offers no other information. Following Beacon for Freedom of Expression's sources again brings you to [FileRoom](https://www.thefileroom.org/documents/dyn/DisplayCase.cfm/id/80) , but that mostly discusses one of Pascal's other works. FileRoom cites another source, *Banned Books 387 B.C. to 1978 A.D.*, but it is a physical book that I don't have access to. So why was *Pensées* banned? I've read articles online about the book, but they all praise it and don't mention anything about it being heretical. The only thing I could think of would be that the French Revolution was happening the same year it was banned, but I don't know how that would affect Pascal's works.