I am undone; literally, cut off, destroyed (comp. Isaiah 15:1; Jeremiah 47:5; Hosea 4:5, Hosea 4:6, etc.). God once said himself, "There shall no man see me and live" (Exodus 33:20). Men expected to die even when they had seen angels of God (Genesis 32:30; 6:22, 6:23; 13:22).
How we are to reconcile Exodus 33:20 with this passage, Job 42:5, and Ezekiel 1:26-28, is uncertain. Perhaps the ecstatic sight was not included in the "seeing" of which God spoke to Moses. I am a man of unclean lips.
A man must be indeed" perfect" never to offend in word (James 3:2). Isaiah felt that he had often so offended. His lips were not "clean" in God's sight, and if not his lips, then not his heart; for "out of the abundance of the heart the mouth speaketh" (Matthew 12:34).
I dwell in the midst of a people of unclean lips. Men catch up the phraseology of their time, and use wrong forms of speech, because they hear them daily. "Evil communications corrupt good manners" (1 Corinthians 15:33).