Pentecost is too big, too vast, too intimidating for any singular explanation, but the Roman liturgy's rich vigil for this feast nurtures the faithful with some food for thought. Let us consider the liturgy of the Roman rite for this great feast, second only to the Sunday of the Resurrection in importance.
The second prophecy is an extraction from Exodus 14, wherein the Pharaoh's forces chase the Israelites through the desert and into the Red Sea, which St. Moses has just parted by the Lord's command. The Lord then tells Moses to close the Sea and drown the Egyptians, which he does. The tract continues the passage:
"Let us sing to the Lord, for He is gloriously magnified: the horse and the rider He hath thrown into the sea: He is become my helper and protector unto salvation...."These two prophecies speak of the same thing, Baptism. Water is a symbol of creation and the essential ingredient of all that lives. Yet water is also uncertain, difficult to control. Genesis chapter 1 speaks of water roaming the earth before it had form. God used water to protect the Israelites from the Egyptians. Egypt itself is a type, a parallel, an example of sin and loss and here God saves His people—fulfilled and most perfectly expressed in the Church—through water. Through water He will "multiply thy seed as the stars of heaven," only He will no longer multiply Abraham's progeny through obedience, but Christ's Church through Sacrament. The second collect of the vigil demands this interpretation:
"O God, who by the light of the New Testament hast made clear to us the miracles wrought in earliest times, prefiguring unto us the Red Sea as an image of the sacred font, and Who in the deliverance of Thy people from the bondage of Egypt, hast foreshadowed the sacraments of the Christian dispensation; grant that all nations who have merited by faith the privilege of the children of Israel, may be born again by partaking of Thy holy Spirit."The third prophecy, take from Deuteronomy 31, compares and contrasts closely with the Ascension of Christ. Moses, nearing death, has taken care to write down his encounters and history with God. He abjures and confronts his fellows Israelites for their infidelity to God, "For I know that, after my death, you will do wickedly, and will quickly turn aside from the way that I have commanded you." The scripture, excluded from this passage, goes on to tell us that his bones were never found. This is extraordinary. Moses joins Elijah, Enoch, and the Blessed Mother among those whose bones have not been found and the others were taken bodily by the Lord, Elijah in a chariot of fire and our Lady after her death in Jerusalem. Moses, a prefigurement of Christ who leads God's people out of bondage, many believe, Jews included, was also taken up by God. Should he have been assumed by God then an strong parallel with the Ascension presents itself. Christ of course was not assumed into heaven, but rather ascended through His own power as God. Moses brought people forth from human bondage and Christ from spiritual bondage. Both died and were raised, so to speak, and rebuked their followers for their lack of faith. Moses's followers would continue to fail God, even if they would eventually reach the promised land and create a kingdom of Israel. Christ, in a marked contrast, promises something perfect that will never be lost, a "Helper" (meaning of the word Paraclete) to preserve the faithful "in all truth." He ascends telling the Apostles to "baptize all nations in the name of the Father and of the Son and of the Holy Ghost.... For I am with you always, even until the end of the world." Moses's deliverance from slavery is made perfect in Christ's words.
The fourth prophecy again anticipates the inception of the Church in the Baptism of its members, "the Lord shall wash away the filth of the daughters of Sion, and shall wash away the blood of Jerusalem out of the midst thereof, by the spirit of judgment, and by the spirit of burning" (Isaiah chapter 4). At this point perhaps the faithful should consider what Baptism is. It is the movement of water over a person's skin with a Trinitarian formula, yes, but it is so much more, too. "Baptism" derives from a similar Greek word meaning "to immerse" or "to plunge." To be "plunged" into Christ and in the name of the Trinity is more than to enter a visible community or lose a sentence of punishments condine to one's sins. To be "plunged" into Christ is to be immersed and filled with the very life of Christ given by the Holy Spirit, Who, St. Gregory reminds the Church of Rome during Mattins of the feast, is the love of God Himself. The Holy Spirit, to be simplistic, is God's love working and doing something, creating or renewing. The Holy Spirit accomplishes this rebirth in Baptism through water, the physical essential in life and the material, again referencing Genesis chapter 1, which formlessly covered the earth before creation. Water is also like the Holy Spirit, or "Holy Wind" to take a very literal translation, in that water is not easily contained, limited, narrowed, or defined. It enters through crevices unseen and can also be lost by poor care through other unanticipated openings. It is this in water that Christ, through the Holy Spirit, renews His creation. It is for this reason so many commentators have adduced the psalm from the Vidi aquam "I saw water flowing from the right side of the Temple, alleluia; and all to whom this water came were saved...." Therefore the Church uses as her last prophecy in the vigil Ezekiel 37:1-14:
"Thus saith the Lord God, Come, spirit, from the four winds, and blow upon these slain, and let them live again. And I prophesied as He had commanded me; and the spirit came unto them; and they lived; and they stood upon their feet, an exceeding great army.... Thus saith the Lord, I will open your graves, and will bring you out of your sepulchres, O My people, and will bring you into the land of Israel.... and you shall have put My spirit in you, and you shall live, and I shall make you rest upon your own land; saith the Lord almighty."
After the baptisms all who have been "baptized into Christ" on earth sing the Litanies of Saints, imploring the intercession of those in heaven who are the perfection of God's promise to Abraham, "multipl[ied] as stars of heaven." The saints, together with those on earth baptized into Christ, form the Church and carry that same Spirit and fire found on Holy Saturday. Pentecost makes the Resurrection permanent on earth, preserved in the Church unto ages of ages.
In a rare moment the Byzantine tradition has a far simpler and more understated take than the Roman Church. The Greek theology of this feast can be found in the troparion of Penteost, which I heard today at Divine Liturgy and last evening at Vespers:
"Blessed are You, O Christ our God, You have filled the fishermen with wisdom by sending down the Holy Spirit upon them, and Who through them have caught in Your net the whole world. O Lover of mankind, glory to You!"