He gave in return the grace of the Holy Spirit

Let us also say a few things about Pentecost, also called "the end of the blessings" which the Resurrected Christ bestowed upon us, "the metropolis of feasts" and "the fruit of the promise". For, with Pentecost human nature receives the abundant blessings of the Paraclete Spirit. Our Lord leaves this earth, but the Holy Spirit comes. The Son and Logos ascends to the unoriginate light-glory, and the all-Holy Spirit transmits this glory to creation! St. John Chrysostom says: "The Lord took up our human nature and sent down the Holy Spirit as proof of the reconciliation of the Father with our own human nature". That is to say, the God-Son ascended in glory into heaven and presented before the amazed angelic powers as a token and guarantee of the work He had accomplished on earth, the first fruits of human nature. As a guarantee and a covenant of the completion of His work of salvation, Christ sent to earth the Third Person of the Holy Trinity, the Paraclete Spirit. This, moreover, shows that Christ reconciled the Father with humanity. And St. Chrysostom uses a familiar image from his time to make even clearer this great truth: Christ received "the first fruits of our nature", and in return gave us "the grace of the Spirit". In other words, what happened is similar to what then used to take place after a long war. When the battles were ended and peace was declared, the opponents, who were previously enemies, would exchange guarantees and earnest agreements. The same thing, in a sense, occurred between God and mankind. Corrupt human nature - under the authority of sin and death, sent to God (the Father) through Christ the select offering as an earnest covenant and guarantee. God in return sent to us the Holy Spirit as a guarantee. We now, therefore, have "a certain guarantee" of the future life and eternal kingdom. The earnest guarantee above in heaven is the "human body" of the Lord, and "down here it is the Holy Spirit coming to us".
The iconography and the worship of the Orthodox Church, which express, each in its own way, the great truths of our faith, underline also this joyous truth. The icon of Pentecost presents the God-called Apostles sitting calmly in a semicircle in the bright upper room, with glad and serene expressions and "the tongues of fire" over their heads, proving that they were "all filled with the Holy Spirit" (Acts 2,3-4). They are holding scrolls as symbols of the teaching authority that was given to them, and which they will use to preach the gospel of repentance to the world with the Cross and the Resurrection at the very core. Under the semicircle where the Apostles sit, in a dark background that rises from the region of abysmal Hades, an old man is depicted with royal garments and crown. In his hand he is holding a sheet with twelve scrolls. The old man symbolizes the world, that has grown old in its sins. It also symbolizes nature that is captive to the "prince of this world". The deep darkness that surrounds the old man represents "the darkness and shadow of death" (Lk. 1,79), Hades, to which the world was enslaved and from which it is already being liberated. The twelve scrolls he holds are symbols of the preaching of the twelve Apostles, who bring light and preach liberty to those captives of death and Hades.
A beautiful hymn for the Sunday of Pentecost blesses the people of the Church who accept the gifts of the Holy Spirit. It says the following:
O you people of the Church, whose faces shine with the light of divine grace, receive the refreshment of the Holy Spirit, which is not only a mere refreshment, but conveys also a burning fire. This refreshment offers the forgiveness and the cleansing of sins; it redeems the soul from the weight of guilt and dispels sins, making you bright and resplendent. For now, on this day of Pentecost, the new redemptive law of the Gospel has come out of the Church; it is the Grace of the Holy Spirit, that has the form of fiery tongues.
The third Prayer of great Vespers for Pentecost also refers to the descent of the Saviour into Hades and invokes divine help for all the dead from the beginning of creation. It contains the following:
Christ our God, You who have broken the strong bonds of death and the bars of Hades and have shown the way below to those sitting down on high; You who through the hopes of resurrection give life to those who are wounded by the sting of death; You, Lord, who manifested on the great and salutary day of Pentecost the mystery of the holy, consubstantial, co-eternal, indivisible and unconfusable Trinity; You who have made us worthy to receive on this perfect and saying feast prayers of mercy for those who have died, give rest to their souls in a place of light, in a place of green pasture, in a place of refreshment, where there is no longer any pain, sorrow or sighing. For it is not the dead who will praise you Lord(...) but we who are alive, we will praise you and beseech you and offer to you prayers of mercy and sacrifices for those souls".
Indeed, the gifts of the Saviour for us humans are great, inconceivable and inexpressible. Christ destroyed the bonds of Hades, and caused the name of death to disappear; He also drowned in the red sea of His blood, the devil, the death and the Hades, our tyrants and persecutors, as other co-rulers and picked officers. Death and Hades suffered a total and disastrous defeat. Let us rejoice, therefore; let us exalt; let us be glad. For, even though it was. "our Lord who defeated the enemy and set up the flag of victory, the gladness and the joy is also common to us human beings". For the Lord did everything for our own definite salvation from the devil, death and Hades.

NIKOLAOS P. VASSILIADIS,
From his Book "THE MYSTERY OF DEATH"
Orthodox Brotherhood of Theologians "The Saviour"