Dominum et Vivificantem §41

⁴¹ The Old Testament on several occasions speaks of "fire from heaven" which burnt the oblations presented by men. By analogy one can say that the Holy Spirit is the "fire from heaven" which works in the depth of the mystery of the Cross. Proceeding from the Father, he directs toward the Father the sacrifice of the Son, bringing it into the divine reality of the Trinitarian communion. if sin caused suffering, now the pain of God in Christ crucified acquires through the Holy Spirit its full human expression. Thus there is a paradoxical mystery of love: in Christ there suffers a God who has been rejected by his own creature: "They do not believe in me!"; but at the same time, from the depth of this suffering-and indirectly from the depth of the very sin "of not having believed"-the Spirit draws a new measure of the gift made to man and to creation from the beginning. In the depth of the mystery of the Cross, love is at work, that love which brings man back again to share in the life that is in God himself. The Holy Spirit as Love and Gift comes down, in a certain sense, into the very heart of the sacrifice which is offered on the Cross. Referring here to the biblical tradition, we can say: He consumes this sacrifice with the fire of the love which unites the Son with the Father in the Trinitarian communion. And since the sacrifice of the Cross is an act proper to Christ, also in this sacrifice he "receives" the Holy Spirit. He receives the Holy Spirit in such a way that afterwards-and he alone with God the Father- can "give him" to the Apostles, to the Church, to humanity. He alone "sends" the Spirit from the Father. He alone presents himself before the Apostles in the Upper Room, "breathes upon them" and says: "Receive the Holy Spirit; if you forgive the sins of any, they are forgiven," as John the Baptist had foretold: "He will baptize you with the Holy Spirit and with fire." With those words of Jesus, the holy Spirit is revealed and at the same time made present as the Love that works in the depths of the Paschal Mystery, as the source of the salvific power of the Cross of Christ, and as the gift of new and eternal life. This truth about the Holy Spirit finds daily expression in the Roman liturgy, when before Communion the priest pronounces those significant words; "Lord Jesus Christ, Son of the living God, by the will of the Father and the work of the Holy Spirit your death brought life to the world...." And in the Third Eucharistic Prayer, referring to the same salvific plan, the priest asks God that the Holy Spirit may "make us an everlasting gift to you."