Dominum et Vivificantem §52

⁵² In the mystery of the Incarnation the work of the Spirit "who gives life" reaches its highest point. It is not possible to give life, which in its fullest form is in God, except by making it the life of a Man, as Christ is in his humanity endowed with personhood by the Word in the hypostatic union. And at the same time, with the mystery of the Incarnation there opens in a new way the source of this divine life in the history of mankind: the Holy Spirit. The Word, "the first-born of all creation," becomes "the first-born of many brethren." And thus he also becomes the head of the Body which is the Church, which will be born on the Cross and revealed on the day of Pentecost-and in the Church, he becomes the head of humanity: of the people of every nation, every race, every country and culture, every language and continent, all called to salvation. "The Word became flesh, (that Word in whom) was life and the life was the light of men...to all who received him he gave the power to become the children of God." But all this was accomplished and is unceasingly accomplished "by the power of the Holy Spirit." For as St. Paul teaches, "all who are led by the Spirit of God" are "children of God." The filiation of divine adoption is born in man on the basis of the mystery of the Incarnation, therefore through Christ the eternal Son. But the birth, or rebirth. happens when God the Father "sends the Spirit of his Son into our hearts." Then "we receive a spirit of adopted sons by which we cry 'Abba, Father!'" Hence the divine filiation planted in the human soul through sanctifying grace is the work of the Holy Spirit. "It is the Spirit himself bearing witness with our spirit that we are children of God, and if children, then heirs, heirs of God and fellow heirs with Christ." Sanctifying grace is the principle and source of man's new life: divine, supernatural life The giving of this new life is as it were God's definitive answer to the Psalmist's words, which in a way echo the voice of all creatures: "When you send forth your Spirit, they shall be created; and you shall renew the face of the earth." He who in the mystery of creation gives life to man and the cosmos in its many different forms, visible and invisible, again renews this life through the mystery of the Incarnation. Creation is thus completed by the Incarnation and since that moment is permeated by the powers of the Redemption, powers which fill humanity and all creation. This is what we are told by St. Paul, whose cosmic and theological vision seems to repeat the words of the ancient Psalm: creation "waits with eager longing for the revealing of the sons of God," that is, those whom God has "foreknown" and whom he "has predestined to be conformed to the image of his Son." Thus there is a supernatural "adoption," of which the source is the Holy Spirit, love and gift. As such he is given to man. And in the superabundance of the uncreated gift there begins in the heart of all human beings that particular created gift whereby they "become partakers of the divine nature." Thus human life becomes permeated, through participation, by the divine life, and itself acquires a divine, supernatural dimension. There is granted the new life, in which as a sharer in the mystery of Incarnation "man has access to the Father in the Holy Spirit." Thus there is a close relationship between the Spirit who gives life and sanctifying grace and the manifold supernatural vitality which derives from it in man: between the uncreated Spirit and the created human spirit.