Paternae §3

³ However, there are some things which are so important for the progress of the Catholic religion that it does not suffice to mention them only once; they demand to be recalled and recommended often. Such is the concern for establishing seminaries, to the condition of which the future fortunes of tae Church are intimately joined. Therefore, in setting up their discipline, that which some bishops have already performed should be your highest priority: that the aspirants to the priesthood should live in special houses called "seminaries" with their own rules and laws. The houses for young people destined for civil life, can be called episcopal colleges. Experience indicates that mixed seminaries do not respond effectively to the plan and the wisdom of the Church. This common life with the laity is the principal reason clerics abandon their vocation. We should accustom future clerics from an early age to bear the yoke of the Lord, to find time for spiritual exercises, to be devoted to their sacred duties, and to conform themselves to the example of the priestly life. Therefore, they should be protected from dangers, separated from everything worldly, and educated according to the rules set forth by Saint Charles Borromeo just as We see accomplished in the major seminaries of Europe.