The Disciples - tradition relates that they were gathered in the Upper Room where they had shared the Last Supper with Christ. St. Peter and Paul, the pillars of the Church, are at the center. This reveals the eternal nature of the feast since St. Paul was not in attendance when Pentecost was held.
The Books The books of the Gospels and scrolls are held in the hands of Disciples who wrote them for the New Testament. This place of honor, formally occupied by the physical person of Christ, is now occupied by the Book of the Gospels which the Holy Spirit has made into the spiritual presence of Christ in the world. This is shown in the tongues of fire which appear over the heads of the Disciples.
The World The entire cosmos received the outpouring of the holy Spirit. This is iconographically symbolized by a crowned figure seated in the midst of the Disciples. He holds in a cloth twelve scrolls. This represents the reception by the entire world of the preaching of the twelve disciples.
In the Old Testament Pentecost was the feast which occurred 50 days after Passover. As the Passover feast celebrated the exodus of the Israelites from the slavery of Egypt, so Pentecost celebrated God's gift of the ten commandments to Moses on Mt. Sinai.
In the new covenant of the Messiah, the Passover event takes on its new meaning as the celebration of Christ's death and resurrection, the "exodus" of men from this sinful world to the Kingdom of God. And in the New Testament as well, the Pentecost feast is fulfilled and made new by the coming of the "new law," the decent of the Holy Spirit upon the disciples of Christ. The apostles received "the power from on high," and they began to preach and bear witness to Jesus as the risen Christ, the King and Lord. This moment has traditionally been called the birthday of the Church.
Once again it must be noted that the feast of Pentecost in not simply the celebration of an event which took place centuries ago. It is the celebration of what must happen and does happen to us in the church today. We all have died and risen with the Messiah-King, and we all have received his Most Holy Spirit. We are the "temples of the Holy Spirit," God's Spirit dwells in us. We, by our own membership in the Church, have received the "seal of the gift of the Holy Spirit" in the Sacrament of Chrismation. Pentecost has happened to us. (Taken from "The Orthodox Faith" Vol. II by Fr. Thomas Hopko)
BLESSED ARE YOU, O CHRIST OUR GOD! YOU HAVE REVEALED THE FISHERMEN AS MOST WISE, BY SENDING DOWN UPON THEM THE HOLY SPIRIT: THROUGH THEM, YOU DREW THE WORLD INTO YOUR NET! O LOVER OF MANKIND, GLORY TO YOU!
WHEN THE MOST HIGH CAME DOWN AND CONFUSED THE TONGUES, HE DIVIDED THE NATIONS, BUT WHEN HE DISTRIBUTED THE TONGUES OF FIRE HE CALLED ALL TO UNITY. THEREFORE WITH ONE VOICE WE GLORIFY THE ALL HOLY SPIRIT!