68 There are some regions, where the dioceses are small, or students unhappily few, or where there is a shortage of means and suitable men. Hence it is impossible for every diocese to have its own seminary, equipped according to all the regulations of Canon Law and other prescriptions of the Church. Where this happens, it is most proper that the Bishops of the district should help one another in brotherly charity, should concentrate and unite their forces in a common seminary, fully worthy of its high purpose. The great advantages of such concentration amply repay the sacrifices entailed in obtaining it. It is indeed a sacrifice, grievous to the fatherly heart of a Bishop, to see his clerics, even for a time, taken away from their shepherd, who wishes himself to give his future co-workers his own apostolic spirit; and to see them taken away from the diocese which is to be the field of their ministry. But these sacrifices will all be repaid with interest when these clerics return as priests. They will be better formed, and more richly endowed with spiritual wealth, which they will spend with greater generosity and with greater profit to their diocese. Therefore, We have never let pass an opportunity to favor, and encourage and foster such efforts. Often, in fact, We have suggested and recommended them. On Our part, also, wherever We thought it necessary, We have Ourselves, as is well known, erected or improved or enlarged several such regional seminaries, not without heavy expense and trouble; and We will continue in the future, by the help of God, to apply Ourselves with all zeal to this work; for We hold it to be the most conducive to the good of the Church.
Source: Ad Catholici Sacerdotii (Vatican.va)