Like many of the old prophets, John taught by symbol as well as by word. The preparation needed was an inward cleansing, and what more fitting symbol of it than the water baptism to which he called the nation? "In that day," it was written in the prophets, "there shall be a fountain opened to the house of David and to the inhabitants of Jerusalem, for sin and for uncleanness." The prophecy was about to be fulfilled, and the baptism of John was the appropriate sign of it. Again, in another of the prophets the promise ran, "Then will I sprinkle clean water upon you, and ye shall be clean; from all your filthiness and from all your idols will I cleanse you ... and I will put my spirit within you." John knew well that it was not given to him to _fulfil_ this promise. He could not grant the real baptism, the baptism of the Holy Ghost; but he could baptise with water; he could give the sign and assurance to the truly penitent heart that there was forgiveness and cleansing in the coming One; and thus, by his baptism with water, as well as by the message he delivered, he was preparing the way of the Lord. All this, we cannot but observe, was in perfect accord with the wonderful prophetic utterance of his father Zacharias, as recorded by St. Luke: "Thou, child, shalt be called the prophet of the Highest: for thou shalt go before the face of the Lord to prepare His ways; to give knowledge of salvation unto His people by the remission of their sins,"--not to give salvation, which only Christ can give, but the knowledge of it. This he did not only by telling of the coming Saviour, and, when He came, pointing to Him as "the Lamb of God that taketh away the sin of the world;" but also by the appropriate sign of baptism, which gave the same knowledge in the language of symbol addressed to the eye.