Isaiah - Chapter 6
Holy, Holy, Holy
This chapter contains Isaiah's very first prophecy. It says that it occurred in the year that King Uziyahu died, but it is generally accepted that it means the year he was struck with tzaraas (leprosy). In his vision, Isaiah saw the throne of G-d. (This is an anthropomorphism; of course, G-d has no literal body or physical throne.) G-d's "lower half" filled the Temple and six-winged Seraphim were praising Him. The Seraphim would call to each other, "Holy, holy, holy is the L-rd of Hosts, the whole world is full of His glory" (which we say in Kedusha, from this source).
The doorways of the Temple shook from the voice of the angels and the Temple filled with smoke. Isaiah was frightened that he would die from seeing G-d's Presence. One of the angels took a coal from the altar and touched Isaiah's mouth with it, purifying him of his sins.
Then G-d asked whom He should appoint messenger and Isaiah volunteered. G-d told him to say to the people, "You hear, but you don't understand; you see, but you don't know. The people are becoming complacent and they're ignoring the words of the prophets, so they won't have to repent." Isaiah asked how long the people will not listen and G-d replied until the cities are all exiled and empty. G-d will carry the people away and only ten percent will remain. Then they will be purged again, like trees that lose their leaves in several shifts until nothing remains but a bare trunk.