In the year King Uzziah died, I saw the Lord seated on a high and lofty throne, with the train of his garment filling the temple. Seraphim were stationed above.-- Isaiah 6:1-2a, 3-7
They cried one to the other, “Holy, holy, holy is the LORD of hosts! All the earth is filled with his glory!” At the sound of that cry, the frame of the door shook and the house was filled with smoke.
Then I said, “Woe is me, I am doomed! For I am a man of unclean lips, living among a people of unclean lips; yet my eyes have seen the King, the LORD of hosts!” Then one of the seraphim flew to me, holding an ember that he had taken with tongs from the altar.
He touched my mouth with it, and said, “See, now that this has touched your lips, your wickedness is removed, your sin purged.”
The lips are a sensitive part of the body, filled with nerves. But for Isaiah to be able to stand in the presence of the Holy One of Israel, Isaiah's very lips are purged with a searing ember. The chastisements we suffer, in our lives and in Purgatory, are necessary if we are to withstand the Glory. There is no other Way but that of the Cross.