Roman Catechism 29.27

Chapter 29 — Part III: The Decalogue — The Sixth Commandment

Section 27. In the same class are to be numbered soft and obscene books which must be avoided no less than indecent pictures. All such things possess a fatal influence in exciting to unlawful attractions, and in inflaming the mind of youth. In these matters the pastor should take special pains to see that the faithful most carefully observe the pious and prudent regulations of the Council of Trent.