The vision kindled as with a flash Isaiah's consciousness of sin. He expressed it in regard to his words rather than his works, partly because in one aspect speech is even more accurately than act a cast, as it were, of character, and partly because he could not but feel the difference between the mighty music that burst from these pure and burning lips and the words that flowed from and soiled his own. Not only the consciousness of sin, but the dread of personal evil consequences from the vision of the holy God, oppressed his heart. We see ourselves when we see God. Once flash on a heart the thought of God's holiness, and, like an electric search-light, it discloses flaws which pass unnoticed in dimmer light. The easy-going Christianity, which is the apology for religion with so many of us, has no deep sense of sin, because it has no clear vision of God. I have heard of Thee by the hearing of the ear; but now mine eye seeth Thee: wherefore I abhor myself, and repent in dust and ashes.'
The next stage in Isaiah's experience is that sin recognised and confessed is burned away. Cleansing rather than forgiveness is here emphasised. The latter is, of course, included, but the main point is the removal of impurity. It is mediated by one of the seraphim, who is the messenger of God, which is just a symbolical way of saying that God makes penitents partakers of His holiness,' and that nothing less than a divine communication will make cleansing possible. It is effected by a live coal. Fire is purifying, and the New Testament has taught us that the true cleansing fire is that of the Holy Spirit. But that live coal was taken from the altar. The atoning sacrifice has been offered there, and our cleansing depends on the efficacy of that sacrifice being applied to us.
The third stage in the prophet's experience is the readiness for service which springs up in his purged heart. God seeks for volunteers. There are no pressed men in His army. The previous experiences made Isaiah quick to hear God's call, and willing to respond to it by personal consecration. Take the motive-power of redemption from sin out of Christianity, and you break its mainspring, so that the clock will only tick when it is shaken. It is the Christ who died for our sins to whom men say, Command what Thou wilt, and I obey.'
