And it shall come to pass in that day, that the mountains shall drop down new wine, and the hills shall flow with milk, and all the rivers of Judah shall flow with waters, and a fountain shall come forth of the house of the LORD, and shall water the valley of Shittim (Joel 3:18).
When Joel said this in Chapter 3, he was continuing his conversation from Chapter 2:
For, behold, in those days, and in that time .... (Joel 3:1).
In Chapter 2, Joel prophesied the outpouring of the Holy Ghost:
And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions (Joel 2:28).
We know that Joel was talking about the outpouring of the Holy Ghost because on the day of Pentecost, the Apostle Peter said:
..... we do hear them speak in our tongues the wonderful works of God. And they were all amazed, and were in doubt, saying one to another, What meaneth this? Others mocking said, These men are full of new wine. But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all ye that dwell at Jerusalem, be this known unto you, and hearken to my words: For these are not drunken, as ye suppose, seeing it is but the third hour of the day. But this is that which was spoken by the prophet Joel; And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams (Acts 2:11-18).
This part of scripture is beautiful in irony! The multitude thought that the one hundred and twenty (including Mary, the mother of Jesus - Acts 1:14,15) from the Upper Room were drunk on sweet fermented wine (Acts 2:13), but instead, they were drunk in the new wine, the Holy Ghost. I think the most beautiful site in this world is seeing someone drunk in the Holy Ghost.
The disciples of John the Baptist asked Jesus why doesn't His disciples fast like they do and like the Pharisees do (Matthew 9:14). Jesus's first response is that while He was still physically with Him, it was a time to celebrate, and that after He was gone, they would have plenty of time to fast (Matthew 9:15).
Jesus's second response (Matthew 9:16) was that the Law (the old garment) could not be joined with the Gospel of Jesus Christ (the new garment). The Pharisees represented the Law and as we know they refused to accept the gospel that Jesus taught.
Now we come to the Lord's third response:
Nor do they put new wine into old wineskins, or else the wineskins break, the wine is spilled, and the wineskins are ruined. But they put new wine into new wineskins, and both are preserved (Matthew 9:17 NKJV).
The "old wineskins" were the Pharisees. Jesus was telling us that they were not about to receive the baptism of the Holy Ghost, the new wine. Instead, the new wineskins, believers, would be filled with the Holy Ghost. And we know that is true when He proclaimed at the great day of the feast:
If any man thirst, let him come unto me, and drink. He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water. (But this spake he of the Spirit, which they that believe on him should receive: for the Holy Ghost was not yet given; because that Jesus was not yet glorified) (John 7:37,38,39).
Likewise, we also know that He prophesied that believers would speak in a new tongue:
And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues (Mark 16:17).