6 Let the seminaries be jealously guarded in order that a proper atmosphere will be maintained. Let them always be destined exclusively for preparing youths, not for civil careers, but for the noble vocation of being ministers of Christ. Let philosophy, theology, and the related sciences, especially Sacred Scripture, be studied along the lines of pontifical directives: according to the teaching of Saint Thomas which Our venerable Predecessor so often recommended, and We Ourselves recommended in the Apostolic Letter of January 23, 1904. Therefore, let the Bishops exercise the most prudent vigilance towards the professors' teachings. Let them recall those who run after certain dangerous novelties to their sense of duty. If they do not profit from these warnings, let them be removed - cost what it may - from their teaching position. Young clerics are forbidden to frequent the universities unless the Bishops think there are very good reasons and necessary precautions have been taken. Seminarians are absolutely forbidden to take part in external activities. Accordingly. We forbid them to read newspapers and periodicals, excepting, in the case of the latter, those with solid principles and which the Bishop deems suitable for their study. Let discipline continue to be fostered with renewed vigor and vigilance. Finally, in every seminary there must be a spiritual director. He is to be a man of extraordinary prudence and experienced in the ways of Christian perfection. With untiring zeal he must train the young men in solid piety, the primary foundation of the spiritual life. Venerable Brethren, if these rules are conscientiously and religiously followed they will be your sure guarantee of seeing a clergy growing up around you which will be your joy and your crown.
Source: Pieni L'Animo (Vatican.va)