What is Pentecost? The Sound of the Wind and the Spirit.

Jesus commanded the apostles that they should not depart from Jerusalem, but wait for the promise of the Father, the baptism of the Holy Ghost. (Acts 1:4-5) The Holy Ghost is the Spirit of Jesus in us. (John 14:17-18)

"If ye love me, keep my commandments. And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever; even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you. I will not leave you comfortless: I will come to you." - John 14:15-18

"And when the day of Pentecost was fully come, they were all with one accord in one place." - Acts 2:1

Jesus had told Nicodemus, a ruler of the Jews, that except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. (John 3:5) Jesus compared being born of the Spirit to the wind.

"The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit." - John 3:8

On the day of Pentecost, there was a sound of wind - a rushing mighty wind.

"And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting." - Acts 2:2

Just as Jesus said, when those in the upper room were born of the Spirit, there was a sound as a wind.

The Bible says the sound came from heaven.  This sound from heaven was the sound of other tongues (other languages) as the Spirit gave them utterance. 

"The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit." - John 3:8

No one could see where the Spirit of Jesus came from, and where it went as it filled each of the disciples, but they heard the sound!

"And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:4