“In the Old Testament, the Holy Spirit prepared the coming of the Word in the flesh, and the Word, having once become incarnate, prepares the coming of the Spirit who will, until the end of the world, prepare for the second coming, in glory, of the incarnate Word, risen and exalted. "Through the mouth of the prophets the whole of the Old Testament is a preliminary Pentecost in view of the appearance of the Virgin and her Fiat." After-wards, ‘Pentecost appears as the ultimate purpose of the trinitarian economy of salvation.’”
“The Word and the Holy Spirit are the two persons who together accomplish and jointly bring to fulfillment the whole of revelation and of its efficacy until the end of the world. To use the expression of Saint Irenaios, they are ‘the two hands of the Father,’ that is, the two active persons. Together they render the Father more and more transparent: ‘The brightness of the Trinity radiates outwards progressively.’ Between the Word and the Holy Spirit exists a continuous reciprocity of revelation and both bring about a common revelation of the Father, and a common spiritualization of creation.”
“The basis of faith in the Trinity, however, is Christ, as a revelation of the Trinity made concrete and brought to its climax. Saint Cyril says: ‘That is why God says, 'Behold, I am laying for the foundations of Zion a chosen stone, a cornerstone, and precious' (Is 28.16, LXX).’”
“Through the incarnate Son we enter into filial communion with the Father, while through the Spirit we pray to the Father or speak with him as sons. For the Spirit unites himself with us in prayer. "It is the Spirit in whom we worship, and in whom we pray... Therefore, to adore of to pray in the Spirit seems to me to be simply himself offering prayer or adoration to himself." But this prayer which the Spirit offers, within us, he offers to himself in our name, and into this prayer we too are drawn. Through grace the Spirit identifies himself with us so that, through grace, we may identify ourselves with him.
Through grace the Spirit eliminates the distance between our "I" and his "I," creating between us and the Father, through grace, the same relation he has by nature with the Father and the Son. If in the incarnate Son we have become sons by grace, in the Spirit we gain the consciousness and boldness that come from being sons.”