Daniel 4, the madness of Nebuchadnezzar (the fourth chapter of the Bible's Book of Daniel) tells how King Nebuchadnezzar learns the lesson of God's sovereignty, "who is able to bring low those who walk in pride." Nebuchadnezzar dreams of a great tree that shelters the whole world, but in his dream an angelic "watcher" appears and decrees that the tree must be cut down and that for seven years he, Nebuchadnezzar, will have his human mind taken away and will eat grass like an ox. This comes to pass, and at the end of his punishment Nebuchadnezzar praises God. (Daniel's role is to interpret the dream for the king).
The message of Nebuchadnezzar's madness is that all earthly power, including that of kings, is subordinate to the power of God. It forms a contrasting pair with chapter 5: Nebuchadnezzar learns that God alone controls the world and is restored to his kingdom, while Belshazzar fails to learn from Nebuchadnezzar's example and has his kingdom taken from him and given to the Medes and Persians.
(Summary of Daniel 4 based on the translation of C.L. Seow in his commentary on Daniel)
Nebuchadnezzar, King of Babylon, addresses a letter "to all peoples, nations and languages that live throughout the earth" telling them he will recount the "signs and wonders" that the Most High God has worked for me."
Nebuchadnezzar was living in his palace in peace and prosperity when he had a strange dream that troubled him. None of his diviners and magicians were able to explain it for him, and he called for Daniel, chief of all his wise men. This is the dream: The king saw a great tree at the centre of the earth, its top touching heaven, visible to the ends of the earth, and providing food and shelter to all the creatures of the world. As the king watched he saw a "holy watcher" come from heaven and call for the tree to be cut down and his (sic – the pronoun changes from "it" to "he") human mind changed to that of a beast for seven "times". This sentence "is rendered by decree of the watchers ... in order that all who live may know that the Most High is sovereign over the kingdom of mortals..."
Daniel explains: the king himself is the tree, and by the decree of God he will lose his human mind for the mind of an animal, and live with wild animals and eat grass like an ox. This came to pass, until at the end of the seven years Nebuchadnezzar had his human mind and his kingdom were restored. The letter concludes with Nebuchadnezzar's praise of God, for "all his works are truth, and his ways are justice, and he is able to bring low those who walk in pride."