1 Our Most Merciful Redeemer, after He had wrought salvation for mankind on the tree of the Cross and before He ascended from out this world to the Father, said to his Apostles and Disciples, to console them in their anxiety, "Behold I am with you all days, even to the consummation of the world." ( Matt . xxviii, 20). These words, which are indeed most pleasing, are a cause of all hope and security, and they bring us, Venerable Brethren, ready succor, whenever we look round from this watch-tower raised on high and see all human society laboring amid so many evils and miseries, and the Church herself beset without ceasing by attacks and machinations. For as in the beginning this Divine promise lifted up the despondent spirit of the Apostles and enkindled and inflamed them so that they might cast the seeds of the Gospel teaching throughout the whole world; so ever since it has strengthened the Church unto her victory over the gates of hell. In sooth, Our Lord Jesus Christ has been with his Church in every age, but He has been with her with more present aid and protection whenever she has been assailed by graver perils and difficulties. For the remedies adapted to the condition of time and circumstances, are always supplied by Divine Wisdom, who reacheth from end to end mightily, and ordereth all things sweetly ( Wisdom viii, 1). But in this latter age also, "the hand of the Lord is not shortened" ( Isaias lix, 1), more especially since error has crept in and has spread far and wide, so that it might well be feared that the fountains of Christian life might be in a manner dried up, where men are cut off from the love and knowledge of God. Now, since it may be that some of the people do not know, and others do not heed, those complaints which the most loving Jesus made when He manifested Himself to Margaret Mary Alacoque, and those things likewise which at the same time He asked and expected of men, for their own ultimate profit, it is our pleasure, Venerable Brethren, to speak to you for a little while concerning the duty of honorable satisfaction which we all owe to the Most Sacred Heart of Jesus, with the intent that you may, each of you, carefully teach your own flocks those things which we set before you, and stir them up to put the same in practice.
Source: Miserentissimus Redemptor (Vatican.va)