Immoral literature includes pornography and books which incite to violence or other reactions against the accepted social morality. Ideologically deviant literature may be classed as immoral by government policy.
Immoral literature leads to depravity. The problem is aggravated by new methods of communication and distribution.
"Lies are boldly insinuated...into weighty tomes and slender volumes, into the transient pages of periodicals and the extravagant advertisements of the theater." We see "books and magazines written to mock virtue and exalt depravity." And in this day of ours_we also have radio broadcasts, motion pictures, and television (which can enter easily into the home). All of these can provide inspiration and incentive for morality and goodness, even Christian virtue. Unfortunately, however, they can also entice men, especially the young, to loose morality and ignoble behavior, to treacherous error and perilous vice. (Papal Encyclical, Ad Petri Cathedram, 29 June 1959).
More than ever nowadays an extended and careful vigilance is necessary, inasmuch as the dangers of moral and religious shipwreck are greater for inexperienced youth. Especially is this true of impious and immoral books, often diabolically circulated at low prices; of the cinema, which multiplies every kind of exhibition; and now also of the radio, which facilitates every kind of communications. These most powerful means of publicity, which can be of great utility for instruction and education when directed by sound principles, are only too often used as an incentive to evil passions and greed for gain. How often today must parents and educators bewail the corruption of youth brought about by the modern theater and the vile book! (Papal Encyclical, Rappresentanti in Terra, 31 December 1929)