57 All the more reason why the young clergy, because they are to be trained in the spiritual life, in sacerdotal and religious perfection, must be separated from the tumult of the world before entering the lists of combat; for long years they must remain in a Seminary or Scholasticate where they receive a sound and careful education which provides them with a gradual approach to and a prudent knowledge of those problems which our times have brought to the fore, in accordance with the norms which We established in the Apostolic Exhortation "Menti Nostrae." What gardener would expose young plants, choice indeed but weak, to violent storms in order that they might give proof of the strength which they have not yet acquired? Seminarians and scholastics are surely to be considered like young and weak plants who must still be protected and gradually trained to resist and to fight.
Source: Sacra Virginitas (Vatican.va)