Verse 1 mentions the death of King Uzziah. He was the tenth king of Judah and he was a very godly man. He was highly influenced by a prophet named Zechariah (though this is a different Zechariah) and, unlike many of the other kings, he never totally departed from the worship of the true God. Under his influence, the southern kingdom attained power, wealth and success unlike any it had enjoyed since the days of Solomon. Made heady by his success as king and by his blessings from the Lord, Uzziah made the mistake of offering incense in the Temple, 2 Chron. 26. He was stricken with leprosy by the Lord for his disobedience to the Lord. He died in that leprous condition! Disobedience to the Lord is a serious thing!
Well, evidently, Isaiah is disturbed by the death of the great king. After all, he had reigned for 52 years. His death signaled the end of a time of great prosperity and consistency. For Isaiah and the entire nation, it ushered in a time of uncertainty, change and doubt. Yet, for Isaiah, this is to be a time of rediscovery. Apparently Isaiah had his attention focused on Uzziah, but now that Uzziah is dead, his attention is redirected back to the Lord.