9 The students should be so saturated with the mystery of the Church, especially as described by this sacred synod, that, bound to the Vicar of Christ in a humble and trusting charity and, once ordained priests, adhering to their own bishop as faithful helpers and engaging in a common effort with their fellow-priests, they bear witness to that unity that attracts men to Christ. They should learn to take part with a generous heart in the life of the whole Church in accord with what St. Augustine wrote: "to the extent that one loves the Church of Christ, to that extent does he possess the Holy Spirit." The students should understand most clearly that they are not destined for domination or for honors but are given over totally to the service of God and to the pastoral ministry. With a particular concern should they be so formed in priestly obedience, in a simple way of life and in the spirit of self-denial that they are accustomed to giving up willingly even those things which are permitted but are not expedient, and to conform themselves to Christ crucified. The students are to be made clearly aware of the burdens they will be undertaking, and no problem of the priestly life is to be concealed from them. This is to be done, however, not that they should be almost solely concerned with the notion of danger in their future labors, but rather that they might be more readily conformed to a spiritual life that more than in any other way is actually strengthened by the very pastoral work they do.
Source: Optatam Totius (Vatican.va)