854. The kinds of printed matter forbidden by the Code (Canon 1399) are as follows: (a) the prohibition extends to books, to other published matter (such as magazines and newspapers), and to illustrations that attack religion and what are called “holy pictures” (i.e., images of our Lord and the Saints), if opposed to the mind of the Church; (b) the prohibition extends to published matter dangerous to faith, and therefore to the following; to writings or caricatures that attack the existence of God, miracles or other foundations of natural or revealed religion, Catholic dogma, worship or discipline, the ecclesiastical hierarchy as such, or the clerical or religious state; to those that defend heresy, schism, superstition, condemned errors, subversive societies, or suicide, duelling, divorce; to non-Catholic publications of the Bible and to non-Catholic works on religion that are not clearly free from opposition to Catholic faith; to liturgical works that do not agree with the authentic texts; to books that publish apocryphal indulgences and to printed images of holy persons that would be the occasion of error (e.g., the representation of the Holy Ghost in human form). 855. The mere presence, however, of condemned matter in a writing does not cause it to fall under prohibition. (a) Some works are not forbidden unless the author’s purpose to teach error or attack the truth is known. Hence, books on religion written by non-Catholics which contain errors against the Catholic Faith are not forbidden, unless they deal with religion _ex professo_ (i.e., not incidentally or cursorily, but clearly for the purpose of teaching). It is not necessary, however, that religion be the main theme of the book, Similarly, books that attack religion are forbidden, not when attacks are casual or by the way, but when they are made purposely; and the same is true as regards books that insult the clerical state. The purpose is recognized from the declaration of the author, from the nature of the work, from the systematic treatment, length or frequency of argumentation or attack, etc. (b) Other works are not forbidden, unless they contain not only agreement with error, but also argument in defense of error. Thus, books in favor of heresy, schism, suicide, duelling, divorce, Freemasonry, etc., are forbidden when they champion wrong causes by disputing in their behalf. (c) Other works are forbidden, not because they state, but because they approve of error. Such are books that attack or ridicule the foundations of religion or the dogmas of faith, those that disparage worship, those that are subversive of discipline, those that defend proscribed propositions, those that teach and favor superstition, etc.