For this Solemnity of Pentecost, from one of my favorite Cistercian writers, .....
Aelred of Rielvaux (1110-1167), English Cistercian monk
Sermon on the sevenfold voice of the Holy Spirit at Pentecost
(translated from the French: Sermones inediti, éd. Talbot, Rome 1952, 1, 112-114)
"In the beginning, according to God’s plan, God’s Spirit filled the world, “reaching mightily from one end of the earth to the other, and governing all things sweetly.” (Wis 8:1) But where the Spirit’s work of sanctification is concerned, it was on the day of Pentecost that “the Spirit of the Lord filled the world.” (Wis 1:7)
For it is today that this Spirit of sweetness is sent by the Father and the Son to sanctify every creature according to a new plan, in a new way, a new manifestation of the Spirit’s power and strength. Before this, “the Spirit had not been given, because Jesus had not yet been glorified.” (Jn 7:39) … Today, the Spirit, coming from his heavenly abode, is given with all his richness, all his fruitfulness to the souls of mortals.
Thus this divine dew, with its diversity and its spiritual gifts, is spread out over all the earth. And it is true that the fullness of the Spirit’s richness flowed down for us from the highest heaven, since a few days previously, through our earth’s generosity, heaven had received a marvelously sweet fruit… Christ’s humanity is all of earth’s grace; Christ’s Spirit is all of heaven’s sweetness.
Thus, a very salvific exchange was brought about: Christ’s humanity went up from earth to heaven; and today, the Spirit of Christ descended from heaven to us… The Holy Spirit is active everywhere; the Spirit speaks everywhere.
Of course, before the Ascension the Lord’s Spirit was given to the disciples when the Lord said to them: “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained.” (Jn 20:23)
But before Pentecost, the voice of the Holy Spirit was not heard, his shining power was not seen. And knowledge of him had not been given to Christ’s disciples, who had not been confirmed in courage since fear still made them hide in a locked room. But starting on that day, “the voice of the Lord is over the waters; …it lashes forth flames of fire … and all say, ‘Glory!’” (Ps 29:3-9)