NOTES for Isa 6:1-8
For some reason, the Lord needs to send someone. We always want Him to act everywhere and in everything by Himself, directly. But there are at least two reasons why He does not do so. The first is that He is, after all, God and not one of us. Since the incarnation of the Son of God, we often forget this, and then we begin to imagine that He is simply obliged to come down to earth and take part in all our affairs... We forget that His help is not an obligation but a great mercy. The second reason is His respect for our freedom. He wants us to hear His voice not because it is impossible not to hear it, but because we have chosen to listen. He leaves us free to stop our ears—and therefore He sends a human being.
The prophet Isaiah does not ask at all why God needs to send someone. He simply responds instantly to the call: “If You need to send someone, here I am; send me.”