Isaiah 27
27:1 - Leviathan is a dragon-like 
  creature that is pictured as: 
  a) gliding swiftly through the air as a spirit being 
  b) a deadly foe like a coing serpant 
  c) inhabiting the sea which is known as a place that is uncontrolled by humans 
  
This is a description of 
  Satan and his use of world powers. 
  
 Just as in Revelation 12:3, 
  "Then another sign appeared in heaven: an enormous red dragon with 
  seven heads and ten horns and seven crowns on his heads. His tail swept a third 
  of the stars out 
  of the sky and flung them to the earth." 
Notice that the dragon, 
  Leviathan is in the "sky" which is the spiritual dominion of Satan 
  Notice that the dragon or Leviathan has heads. These heads are the world powers 
  that have manifest 
  Satan's cosmos through time: Egypt, Assyria, Babylon, Persia, Greece, Rome, 
  Anti-christ Kingdom 
  
 In Psalms 74:14 it says, 
  "It was you who crushed the heads of Leviathan and gave him as food to the
  creatures of the desert." 
Here Leviathan is seen as having heads also. Or, Satan is pictured as being over the world powers.
In Isaiah 27:1 the first 
  three world powers are mentioned in describing Leviathan: 
  1) "Leviathan the gliding serpent" refers to the straight, fast Tigris river 
  or Assyria 
  2) "Leviathan the coiling serpent" refers to the winding, twisting Euphrates 
  river or Babylon 
  3) "He will slay the monster of the sea" refers to the land of Egypt that is 
  on the Meditterranean Sea. 
Revelation 12:9 identifies 
  Satan this way, "The great dragon was hurled down - that ancient serpent called 
  the devil, or Satan, 
  who leads the whole world astray."
These are three of the heads of Leviathan or three of Satan's world powers.
27:1 begins, "In that day. . ." which refers to an eschatological day in the future.
24:1 has already said "In that day the Lord will punish the powers in the heavens above . . ."
27:2 This begins talking 
  about the vineyard. 
  In Isaiah 5:1-7 the vineyard is introduced as Israel. In Isaiah 5 the vineyard 
  is judged as unproductive. 
  Here in 27:2-5 the nation of Israel has become "a fruitful vineyard." (literlly 
  "a vineyard of wine") 
Through time God has disciplined 
  and corrected Israel until in the end they will achieve the purpose he planned 
  for them. 
  "watch over it" indicates God is constantly aware of and caring for Israel. 
  "water it continually" is literally "daily rising up 
  early and sending them". 
The watering refers to God sending prophets and teachers to Israel through out time to instruct them and help them grow.
27:4 "I am not angry" refers 
  to the day in their future (after Isaiah's day and after the Roman dispersion) 
  when God's work 
  of salvation is done and his wrath has passed.
 This is mentioned in Isaiah 
  40:2, "Speak tenderly to Jerusalem, and proclaim to her that her hard service 
  has been completed,
  that her sin has been paid for, that she has receivd fomr the Lord's hand double 
  for all her sins." 
"Briers and thorns" are 
  rebellious Jews in the vineyard. If they were weeds they'd be burned, but if 
  these repent they will be spared. 
  It is part of God's purifiying the nation and preparing for the fruitful season 
  (millennium) that is coming in verse 6. 
27:6 The millennium production. They will bud and fill the whole earth.
27:7 God did not strike Israel like he struck other nations. The nations were destroyed, but Israel is disciplined.
27:8 God used warfare and exile to correct Israel. They are driven out of their land.
27:9 Israel atones (makes 
  ammends, pays restitution) for their sins by this national discipline. 
  The result is that Israel will become obedient. After the Babylonian captivity 
  Israel never returned to idol worship. 
  The false altars and Asherah poles were destroyed. When Israel returns from 
  captivity they will have had their minds 
  changed and destroy everything pagan from their lives. 
This was also a command 
  they where to follow when they entered the land: 
  Exodus 34:13 
  Dt. 12:2-3 
So, their "atoned" sin is more of a discipline that creates in them a new attitude and a correct world view.
When they return from discipline they will have a divine viewpoint.
 27:10-11 "the fortified 
  city" is? ? ?
  a) the cities of the world (Gentiles) as in other places in chapters 24-27 
  b) Samaria after the Assyrian dispersion 
  c) Jerusalem before the Babylonian captivity. 
The picture is that of an overrun city that is used by cattle to graze in and the unkept, unpruned trees have dead branches.
Trees of a city are usually pruned and cared for. These city trees are growing wild and unkept.
27:11 Why did this happen 
  to either
  a) the cities of the world
  b) Samaria 
  c) Jerusalem 
The people did not "understand" 
  or think like God thinks (some would call it faith).
  They did not have divine viewpoint (faith). 
  No divine viewpoint equals or no faith results in: 
  a) no compassion from God 
  b) no favor from God Describes the people before the judgment and discipline. 
  
This is why Israel is going to be judged.
27:12 The regathering of Israel to their land
 27:13 The regathering of 
  the nations to worship in Jerusalem 
  Also seen in Isaiah 11:12-16 and 35:1-10 
Summary: 
  Chapters 7-12 says that if you trust in the nations they will destroy you 
  Chapters 13-27 says that God will then deliver his people from those nations 
  
Isaiah chapters 28-33 
  Explains the folly of trusting in the nations
 Isaiah lists seven woes 
  in these six chapters: 
  1) "Woe to that wreath, the pride of Ephraim's drunkards." (28"1)
  2) "Woe to you, Ariel, Ariel, the city where David settled!" (29:1) 
  3) "Woe to those who go to great depths to hide their plans from the Lord." 
  (29:15) 
  4) "Woe to the obstinate children. . .to those who carry out plans that are 
  not mine." (30:1) 
  5) "Woe to those who go down to Egypt for help, who rely on horses, who trust 
  in the multitude of their chariots 
  and in the great strength of their horsemen, but do not look to the Holy One 
  of Israel, or seek help from the Lord." (31:1)
  6) "Woe to you, O destroyer, you who have not been destroyed! (33:1) 
  7) "Woe to you, O traitor, you who have not been betrayed!" (33:1) 
28:1-4 Samaria the capital of northern Israel was the glory or wreath of the land. It would be overrun by Assyria
28:5 The Lord would be the glory or the wreath of honor for the believing remnant