John answered them all, "I indeed baptize you with water, but he comes who is mightier than I, the latchet of whose sandals I am not worthy to loosen. He will baptize you in the Holy Spirit and fire,

Luke 3:4-6 are a quotation from Isaiah 40:3-5. When a king proposed to tour a part of his dominions in the east, he sent a courier before him to tell the people to prepare the roads. So John is regarded as the courier of the king. But the preparation on which he insisted was a preparation of heart and of life. "The king is coming," he said. "Mend, not your roads, but your lives." There is laid on everyone of us the duty to make life fit for the King to see. 