Isaiah sees the throne of God, whether literally or symbolically, the effect is the same. Isaiah becomes aware of his uncleanness and the uncleanness of his people. He consequently laments his state having been brought into the presence of God. Subsequently, Isaiah is symbolically cleansed with a live coal from the alter of the temple.
Here is found in verses 9 and 10, a significant passage quoted by the Savior in his ministry:
And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.
Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed.
Then at the end of the chapter is a prophetic contemplation on the fallen state of man. He asks the Lord how long will man remain in this state. The Lord’s answer is until the cities are desolate. In other words, until man is no more.
There is a hopeful reference to a tenth that will remain.