8 We can easily admit that this is very difficult in practice, unless the elements of discord are erased from their souls at an early time when they, who aspire to the clerical state, are formed in our seminaries. Therefore, you must diligently see to it that the students in seminaries early learn to love one another in a fraternal love and from a genuine heart, as those born not from a corruptible seed but an incorruptible one through the word of the living God.(3) Should arguments break out, restrain them strongly and do not allow them to persist in any way; thus those who are destined for the clergy, if they cannot be of one language because of different places of origin, still may certainly be of one heart and one spirit.
Source: Reputantibus (Vatican.va)