Of all human activities, man's listening to God is the supreme act of his reasoning and will.
Pope Paul VIWithout repeating everything that we have already mentioned, it is appropriate first of all to emphasize the following point: for the Church, the first means of evangelization is the witness of an authentically Christian life, given over to God in a communion that nothing should destroy and at the same time given to one's neighbor with limitless zeal. As we said recently to a group of lay people, โModern man listens more willingly to witnesses than to teachers, and if he does listen to teachers, it is because they are witnesses.
Pope Paul VINo member of the faithful could possibly deny that the Church is competent in her magisterium to interpret the natural moral law.
Pope Paul VIPhysics does not change the nature of the world it studies, and no science of behavior can change the essential nature of man, even though both sciences yield technologies with a vast power to manipulate the subject matters.
Pope Paul VI