Isaiah 29 opens with "Woe to Ariel," a poetic name for Jerusalem, the city "where David encamped." Ariel may mean "altar hearth." God would bring the city low, so that its voice would rise "out of the ground," but then the multitude of foes would vanish suddenly, "like a dream, a vision of the night." This fits the sudden defeat of Assyria's army in Isaiah 37.
Spiritually, Jerusalem was in a stupor. Prophets and seers were covered, and God's vision was "like the words of a book that is sealed." The root problem was hypocrisy: "this people draws near with their mouth and honors me with their lips, but they have removed their heart far from me, and their fear of me is a commandment of men which has been taught." In the New Testament, Jesus applies this verse to the Pharisees in Mark 7:6-7, and Paul quotes verse 14 about the wisdom of the wise perishing in 1 Corinthians 1:19.
The planners who hid their counsel from God turned reality upside down, as if clay said of the potter, "He has no understanding." Yet God promised reversal: "the deaf will hear the words of the book, and the eyes of the blind will see." The tyrant and the scoffer would vanish. Jacob would no longer be ashamed, and those who err in spirit would come to understanding. In the New Testament, Jesus points to such signs in answering John the Baptist (Matthew 11:5).