55 Flight and alert vigilance, by which we carefully avoid the occasions of sin, have always been considered by holy men and women as the most effective method of combat in this matter; today however it does not seem that everybody holds the same opinion. Some indeed claim that all Christians, and the clergy in particular, should not be "separated from the world" as in the past, but should be "close to the world;" therefore they should "take the risk" and put their chastity to the test in order to show whether or not they have the strength to resist; therefore, they say, let young clerics see everything so that they may accustom themselves to gaze at everything with equanimity, and thus render themselves immune to all temptations. For this reason they readily grant young clerics the liberty to turn their eyes in any direction without the slightest concern for modesty; they may attend motion pictures, even those forbidden by ecclesiastical censorship; they may peruse even obscene periodicals; they may read novels which are listed in the Index of forbidden books or prohibited by the Natural Law. All this they allow because today the multitudes are fed by this kind of amusement and publication and because those who are minded to help them should understand their way of thinking and feeling. But it is easily seen that this method of educating and training the clergy to acquire the sanctity proper to their calling is wrong and harmful. For "he that loveth danger shall perish in it;" most appropriate in this connection is the admonition of Augustine: "Do not say that you have a chaste mind if your eyes are unchaste, because an unchaste eye betrays an unchaste heart."
Source: Sacra Virginitas (Vatican.va)