31 Remember, above all, that zeal, to be profitable and praiseworthy, must be "accompanied by discretion, rectitude and purity." Thus does the grave and judicious Thomas a Kempis express himself. Before him St. Bernard, the glory of your country in the twelfth century, that indefatigable apostle of all great causes touching the honor of God, the rights of the Church or the good of souls, did not fear to say that "zeal, separated from knowledge and from the spirit of discernment or discretion, is insupportable . . . that the more ardent zeal is, the more necessary is it that it be accompanied by that discretion which puts order into the exercise of charity and without which even virtue may be changed into a defect and a principle of disorder."(19) And discretion in activity and in the choice of means of rendering activity successful is all the more indispensable from the fact that the present times are disturbed and environed with numerous difficulties. This or that act, measure or practice, suggested by zeal, while excellent in themselves, can only - owing to the circumstances of the race - produce bad results. Priests will avoid this inconvenience and this evil, if before and during their action they take care to conform to established order the rules of disciplines. And ecclesiastical discipline demands union among the different members of the hierarchy, and the respect and obedience of inferiors to their superiors. In our recent letter to the Archbishop of Tours we said the same thing: "The edifice of the Church of which God Himself is the architect, rests on a very visible foundation, primarily on the authority of Peter and his successors, but also on the Apostles and the successors of the Apostles, the Bishops, so that to hear their voice or to despise it is tantamount to hearing or despising Jesus Christ Himself."(20)
Source: Depuis le Jour (Vatican.va)