Ad Catholici Sacerdotii §65

⁶⁵ Conscious of this necessity, the Church down the ages has shown for nothing a more tender solicitude and motherly care than for the training of her priests. She is not unaware that, as the religious and moral conditions of peoples depend in great measure upon their priests, so too, the future of the priest depends on the training he has received. The words of the Holy Spirit apply no less truly to him than to others: "A young man according to his way, even when he is old, he will not depart from it." Hence, the Church, moved by the Holy Spirit, has willed that everywhere seminaries should be erected, where candidates for the priesthood may be trained and educated with singular care.