A full-rigged ship under an unfurled sail makes a beautiful picture, but it does not move without wind. Without "the breath of life," human beings cannot perform. An artist needs inspiration. The "ruah Yahweh"----the breath , animating Spirit, of God----was given to us at baptism. On the fiftieth day after Easter (Passover), the Jews celebrated the giving of the Mosaic Law at Sinai and the establishment of Israel as God's people. At Pentecost, we celebrate the giving of the Spirit to God's people and, related to it, the establishment of the new Israel, the Church.
The Spirit, whom the Lord Jesus sends from the Father, will remind us of all that the Lord has taught us. He will animate us and help us to know and understand our religion not just with our mind but also with our heart and soul (Jn 14:26).
Following the example of the Bible, Christians celebrate the mystery of our Lord's Resurrection for fifty days. The Lord's Ascension and Pentecost are the final memorial days. "Our paschal lamb, Christ, has been sacrificed. Therefore, let us celebrate the feast" (1 Cor 5:6-8). "O God, ...grant, we pray, that we who keep the solemnity of the Lord's Resurrection may, through the renewal brought by your Spirit, rise up in the light of life."
The Spirit is seen as a unifying force. It "has filled the whole world" (Wis 1:7)...the Spirit unites by overcoming division caused by misunderstanding. The Spirit is also seen as the "principle of love." Finally, the Spirit is seen as livegiving, as the "ruah Yahweh" ----the breath (spirit) of the God-Creator hovering over the water (Gn. 1:1).
ref. New Saint Joseph - Sunday Missal (2011): Catholic Book Publishing, Corp., N.J., pp. 1222, 371, 481.