4 Major seminaries are necessary for priestly formation. Here the entire training of the students should be oriented to the formation of true shepherds of souls after the model of our Lord Jesus Christ, teacher, priest and shepherd. They are therefore to be prepared for the ministry of the word: that they might understand ever more perfectly the revealed word of God; that, meditating on it they might possess it more firmly, and that they might express it in words and in example; for the ministry of worship and of sanctification: that through their prayers and their carrying out of the sacred liturgical celebrations they might perfect the work oœ salvation through the Eucharistic sacrifice and the sacraments; for the ministry of the parish: that they might know how to make Christ present to men, Him who did not "come to be served but to serve and to give His life as a ransom for many" (Mark 10:45; cf. John 13:12-17), and that, having become the servants of all, they might win over all the more (cf. 1 Cor. 9:19). Therefore, all the forms of training, spiritual, intellectual, disciplinary, are to be ordered with concerted effort towards this pastoral end, and to attain it all the administrators and teachers are to work zealously and harmoniously together, faithfully obedient to the authority of the bishop.
Source: Optatam Totius (Vatican.va)