As Daniel explains the dream we see that, verse 22, Nebuchadnezzar is the tree, with his power and influence clearly recognised and depicted by the spreading branches and growth. But he is a tree that will be cut down, verse 23.
Verse 24 draws a contrast between Nebuchadnezzar's decree in chapter 3:11, and God’s. God's decrees come to pass because he is the ultimate authority, he is King of kings and Lord of lords. God’s decree, the dream, is very specifically “issued against my lord the king.” Nebuchadnezzar has been told in advance what will happen and what will end it in verse 25b.
There is another contrast here in how Nebuchadnezzar sees himself and how God sees him; to Go he is a tree that can be felled even if its “height was enormous…its top touched the sky…visible to the ends of the earth…from it every creature was fed.” Nebuchadnezzar is not as all powerful as he thought, his opinion of himself is wrong and God will humble him. Nebuchadnezzar sees himself as tree and, chapter 3, worthy of worship God sees him as (17, 25, 31) someone he has given power to for a period of time he decrees.
The essence of sin is that I make myself , in a host of ways, the centre of the universe. That is true of Nebuchadnezzar and God will not stand for it. Yet there is also a contrast here between the mercy of God and merciless nature of Neb; (v27) Neb is described as one who oppresses, (c/f ch 3:11, 29) whereas God shows mercy giving Neb warning in dream and sending Daniel who calls him to repent, and it will be seen in his restoration once he has repented. “It may be then that your prosperity will continue” – God may relent if you repent, because he is gracious compassionate. The question as Nebuchadnezzar recounts his testimony is will he? Will he heed the warning, or brashly, brazenly continue to flaunt his power and rule and to deny Gods.
God is gracious and merciful in the warnings he gives his people, in the ways and times he speaks to us. The question is will we listen and repent or stubbornly believe the lie that we are in control?