Charles Spurgeon Commentary Isaiah 6:6-7

"Then flew one of the seraphim unto me, having a live coal in his hand, which he had taken with the tongs from off the altar: and he touched my mouth with it, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin forgiven." — Isaiah 6:6-7 (ASV)

Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar: and he laid it upon my mouth, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.

The live coal from the altar does not represent the holy flame which burns in the prophet's heart; but it represents purgation, cleansing, participation in the sacrifice, and the putting away of sin.

With a blister on his lip, Isaiah stood silent before God.