Priestly celibacy has been guarded by the Church for centuries as a brilliant jewel, and retains its value undiminished even in our time when the out… - Paul VI

We find sin the perversion of human freedom, and the deep cause of death, because it is separation from God, the source of life...and then, in its turn, the occasion and effect of an intervention in us and in our world of an obscure agent, the Devil. Evil is not merely a lack of something, but an effective agent, a living spiritual being, perverted and perverting. A terrible reality. Mysterious and frightening. It is contrary to the teaching of the Bible and the Church to refuse to recognize the existence of such a reality, or to regard it as a principle in itself which does not draw its origin from God like every other creature; or to explain it as a pseudoreality, a conceptual and fanciful personification of the unknown causes of our misfortunes.

With regard to man's innate drives and emotions, responsible parenthood means that man's reason and will must exert control over them.

HUMANAE VITAE tradendae munus gravissimum, ex quo coniuges liberam et consciam Deo Creatori tribuunt operam, magnis semper ipsos affecit gaudiis, quae tamen aliquando non paucae difficultates et angustiae sunt secutae.