I have posted regularly on the relevance of Humanae Vitae for our times. In his encyclical the Pope reminds us of references in Scripture and the Mass to the aggressive and oppressive “power of darkness,” and adds:
So we know that this dark disturbing being exists and that he is still at work with his treacherous cunning; he is the hidden enemy who sows errors and misfortunes in human history. It is worth recalling the revealing Gospel parable of the good seed and the cockle, for it synthesizes and explains the lack of logic that seems to preside over our contradictory experiences: "An enemy has done this." He is "a murderer from the beginning . . . and the father of lies,"[Jn 8:44] as Christ defines him. He undermines man's moral equilibrium with his sophistry. He is the malign, clever seducer who knows how to make his way into us through the senses, the imagination and the libido, through utopian logic, or through disordered social contacts in the give and take of our activities, so that he can bring about in us deviations that are all the more harmful because they seem to conform to our physical or mental makeup, or to our profound, instinctive aspirations.This matter of the Devil and of the influence he can exert on individuals as well as on communities, entire societies or events, is a very important chapter of Catholic doctrine which should be studied again, although it is given little attention today. Here and here are some welcomed attention.