As it is written in the book of the words of Esaias the prophet, saying, voice of one crying in the wilderness. The prophet quoted (Isaiah 40:3) had been writing in his solitude, or more probably in some great popular assembly preaching to the people.
There was doubtless at that time much national trouble threatening Israel; the future of the chosen race looked very dark and gloomy, within and without. We can hear the man of God speaking with intense earnestness, and looking on to brighter times.
"Comfort ye, comfort ye my people, saith your God. Speak ye comfortably to Jerusalem, and cry unto her, that her warfare is accomplished, that her iniquity is pardoned," etc.; and then a sudden burst when the prophet, bending forward and straining his ears to hear some sound none other caught but he, goes on in his rapt utterance—I hear a voice, "The voice of him that crieth in the wilderness, Prepare ye the way of the Lord."
Prepare ye the way of the Lord, make his paths straight. The image is a simple one, and in the East one well knows, where the roads are comparatively few, and where they do exist are often in a bad state, when a sovereign is about to visit any part of his dominions, or still more if the march of an army has to be arranged for, the roads require considerable preparation.
Josephus ('Bell. Jud.,' Luke 3:6) describes the advance of the Emperor Vespasian's army, and specially mentions how the pioneers and the vanguard had to make the road even and straight, and, if it were anywhere rough hard to be passed over, to plane it.
There was a Jewish legend that this special pioneering work in the desert was done by the pillar of cloud and fire, which brought low the mountains and filled the valleys before the Israelitic march.
John's special work was to prepare the way for the advent of a Messiah very different to the one the people looked for—to prepare his way by a spiritual reformation in the heart, the mind, and the character.