No sooner had the king articulated his pride, than he heard a voice from heaven pronouncing the punishment that Daniel had warned might come upon him. Immediately something snapped in his mind and he became like an animal. "Hair as eagle feathers" pictures hair that is neglected and matted as well as long. He did not think to trim his fingernails and toenails, either. His judgment is a sobering reminder that we are all but a breath or a heartbeat from insanity, or death, but for God"s grace. It is He who sustains us moment by moment ( John 15:5; Colossians 1:17). The humbling of proud rulers is a common theme in Scripture (cf. Deuteronomy 17:14-20; Psalm 92; Proverbs 16:5-7; Proverbs 16:12; Isaiah 10:5 to Isaiah 11:10; Isaiah 14:4-23; Ezekiel 17:23-24; Ezekiel 19:10-14; Ezekiel 28; Ezekiel 31:5-6; Ezekiel 31:12-13; Acts 12:23). [source][source][source]
"What he should have learned from his vision of the great image and from the deliverance of the three Hebrews from the fiery furnace would [1] be indelibly impressed on him." [2][source]
"If there"s one message that is emphasized in the Book of Daniel it"s that "the Most High rules in the kingdom of men" ( Daniel 4:32, NKJV)." [3][source]
"Perhaps one should say that the true insanity belongs to the Nebuchadnezzar who has earlier been talking as if he were the eternal king and God did not exist. His outward madness is the external expression of a delusion he has already been the tragic victim of. Only a madman thinks he is a king or an emperor (Pascal): politics is the house rules of a lunatic asylum. But those rules are important, because they make the madness as little harmful as possible." [4][source]
It would not have been abnormal for Nebuchadnezzar"s enemies in Babylon to kill him and take his place. The fact that this did not happen during the time of the king"s breakdown is another tribute to God"s sovereignty. He kept affairs under control, so that when Nebuchadnezzar recovered, he could continue to rule. [5] One wonders what role Daniel might have played in protecting the king, and encouraging the other royal officials to expect and plan for Nebuchadnezzar"s restoration. [source][source][source]