"Here I am, send me". That was the reaction of the prophet Isaiah to the Lord's request for a messenger. But it wasn't an offer of pride or rash self-ambition. Isaiah had a vision of the Lord in the Temple, which made him very conscious of his own sinfulness. But he also became conscious of his sin being taken away, of being cleansed and healed by the Lord. His awareness and gratefulness made him ready for the calling and mission awaiting him. Something similar happened to Peter when he came to realise who Jesus was: he said 'Leave me, Lord, I am a sinful man'. But that was when Jesus told him not to be afraid, and gave him his mission to be a fisher of men. The saints who called themselves the greatest of sinners sometimes seem to us to be exaggerating. But it's their fine sensitivity to who God is, His holiness and greatness and mercy that makes them so conscious of their own nothingness. It's only when we've really acknowledged who God is, and admitted and accepted before Him our own sinfulness and weakness, that we can begin to appreciate His overpowering love. Any vocation is God's grace, not our own power and effort. How generous, zealous and committed any of us are in God's service comes from the power of God's love that we've allowed into our lives by saying "Yes" to His calling.