Dominum et Vivificantem §14

¹⁴ Therefore Jesus Christ says in the Upper Room "It is to your advantage I go away; ...if I go, I will send him to you." The "departure" of Christ through the Cross has the power of the Redemption-and this also means a new presence of the Spirit of God in creation: the new beginning of God's self-communication to man in the Holy Spirit. "And that you are children is proven by the fact that God has sent into our hearts the Spirit of his Son who cries: Abba, Father!" As the Apostle Paul writes in the Letter to the Galatians. The Holy Spirit is the Spirit of the Father, as the words of the farewell discourse in the Upper Room bear witness. At the same time he is the Spirit of the Son: he is the Spirit of Jesus Christ, as the Apostles and particularly Paul of Tarsus will testify. With the sending of this Spirit "into our hearts," there begins the fulfillment of that for which "creation waits with eager longing," as we read in the Letter to the Romans. The Holy Spirit comes at the price of Christ's "departure." While this "departure" caused the Apostles to be sorrowful, and this sorrow was to reach its culmination in the Passion and Death on Good Friday, "this sorrow will turn into joy." For Christ will add to this redemptive "departure" the glory of his Resurrection and Ascension to the Father. Thus the sorrow with its underlying joy is, for the Apostles in the context of their Master's "departure," an "advantageous" departure, for thanks to it another "Counselor" will come. At the price of the Cross which brings about the Redemption, in the power of the whole Paschal Mystery of Jesus Christ, the Holy Spirit comes in order to remain from the day of Pentecost onwards with the Apostles, to remain with the Church and in the Church, and through her in the world. In this way there is definitively brought about that new beginning of the self-communication of the Triune God in the Holy Spirit through the work of Jesus Christ, the Redeemer of man and of the world.