Isaiah's mind was one of the most sensitive and complicated ever bestowed on a human being; but it was now in the hands of its Maker, who knew how to touch it to fine issues. The Maker's design on this occasion was to produce in it an overpowering sense of sin; and what He did was to confront it with infinite holiness and majesty. These were brought so near that there was no escape. The poor, finite, sinful man was held at arm's length, so to speak, in the grasp of the Infinite and Most Holy; and the result was a total collapse of the human spirit. Isaiah's eye turned away from the sight of God's glory back upon himself, and back on his past life; and, in this light, all appeared foul and hideous. There was sin everywhere--sin in himself and sin in his environment. He was utterly confounded and swallowed up of shame and terror. "Woe is me," he groaned, "for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips."
Why he felt the taint specially on his lips it might not be easy to tell. Perhaps it was because the angelic song was a challenge to join in the praise of God, but he felt that the lips of one like him were not worthy to join in their song. Perhaps--who can tell?--the besetting sin of his previous life may have been profanity of speech, as it was evidently a crying sin of his time. This suggestion gives a shock to the ideas which we associate with Isaiah, and it is hard to think that the lips which afterwards spoke like angels can ever have defiled themselves with such a sin. But this is the most natural meaning of the words, and it is not against the analogy of other lives. Great saints, and even great preachers, are made out of great sinners; and the memory of an odious and conspicuous sin like this may sometimes lend a passionate force to subsequent devotion and keep alive for a lifetime the sense of personal unworthiness.
3. The last scene in the evolution of this vision, which was surely more than a vision, was the Vision of Grace. One of the fiery attendants, who hovered on quivering wing ready to execute the orders of the Divine King, receiving a command by some unexplained mode of communication, flew to the altar, and, taking up the tongs, seized with them a stone from the altar fire. It was neither a coal, as our rendering gives it, nor a brand, but a heated stone, such as was used, and is used at the present day, in the East, for conveying heat to a distance for any purpose for which it might be required. It came from the altar: it contained God's fire, and God sent it.
The purpose for which it was required on this occasion was cleansing. Of cleansing there are in Scripture three symbols. The simplest is water; and water can purify many things; but there are some things which water cannot cleanse. A stronger agent is required, and this is found in fire. You must fling the ore, for example, into the fire, if you wish to extract from it the pure gold. There is a third symbol, which appears in the New Testament as well as the Old, and it is the most sacred of all. It is blood. Water, fire, blood--these three mean the same in Scripture. In this case it was fire.
The seraph flew with the hot stone and laid it on the lips of the future prophet. Why did he lay it there? Because it was there that Isaiah felt his sin to be lying. He had said, "I am a man of unclean lips." The fire burned the sin away. So the seraph said, speaking in God's name, "Lo, this hath touched thy lips, and thine iniquity is taken away and thy sin purged." It was the assurance of the Divine forgiveness, which had come swift as a seraph's flight in answer to Isaiah's confession.[10]