'"Having accomplished the work that the Father had entrusted to the Son on earth, on the day of Pentecost the Holy Spirit was sent to sanctify the Church forever, so that believers might have access to the Father through Christ in one Spirit. He is the Spirit of life, the fountain of water springing up to eternal life, the One through whom the Father restores life to those who are dead through sin, until one day he will raise in Christ their mortal bodies."
In this way the Second Vatican Council speaks of the Church's birth on the day of Pentecost. This event constitutes the definitive manifestation of what had already been accomplished in the same Upper Room on Easter Sunday. The Risen Christ came and "brought" to the Apostles the Holy Spirit. He gave him to them, saying "Receive the Holy Spirit." What had then taken place inside the Upper Room, "the doors being shut," later, on the day of Pentecost is manifested also outside, in public. The doors of the Upper Room are opened and the Apostles go to the inhabitants and the pilgrims who had gathered in Jerusalem on the occasion of the feast, in order to bear witness to Christ in the power of the Holy Spirit. In this way the prediction is fulfilled: "He will bear witness to me: and you also are witnesses, because you have been with me from the beginning."
We read in another document of the Second Vatican Council: "Doubtless, the Holy Spirit was already at work in the world before Christ was glorified. Yet on the day of Pentecost, he came down upon the disciples to remain with them for ever. On that day the Church was publicly revealed to the multitude, and the Gospel began to spread among the nations by means of preaching."
The era of the Church began with the "coming," that is to say with the descent of the Holy Spirit on the Apostles gathered in the Upper Room in Jerusalem, together with Mary, the Lord's Mother. The time of the Church began at the moment when the promises and predictions that so explicitly referred to the Counsellor, the Spirit of truth, began to be fulfilled in complete power and clarity upon the Apostles, thus determining the birth of the Church. The Acts of the Apostles speak of this at length and in many passages, which state that in the mind of the first community, whose convictions Luke expresses, the Holy Spirit assumed the invisible - but in a certain way "perceptible" - guidance of those who after the departure of the Lord Jesus felt profoundly that they had been left orphans. With the coming of the Spirit they felt capable of fulfilling the mission entrusted to them. They felt full of strength. It is precisely this that the Holy Spirit worked in them and this is continually at work in the Church, through their successors. For the grace of the Holy Spirit which the Apostles gave to their collaborators through the imposition of hands continues to be transmitted in Episcopal Ordination. The bishops in turn by the Sacrament of Orders render the sacred ministers sharers in this spiritual gift and, through the Sacrament of Confirmation, ensure that all who are reborn of water and the Holy Spirit are strengthened by this gift. And thus, in a certain way, the grace of Pentecost is perpetuated in the Church.'
from Dominum et Vivificantem: On the Holy Spirit in the Life of the Church and the World, 1986
by Pope St John Paul II, 1920-2005
We beseech thee, O Lord, that the Comforter who proceedeth from thee
may enlighten our minds: and lead us, as thy Son hath promised, into all truth;
through Jesus Christ thy Son our Lord, who liveth and reigneth wih thee,
in the unity of the same Holy Ghost, ever one God, world without end. Amen.
Collect for the Ember Wednesday in Whitsun Week from Divine Worship: The Missal
Fr Lee Kenyon
Priest, Husband, Father, Lancastrian, Mancunian