Roads of Bible times were little more than paths, rough and crude by modern standards. When a king traveled, his servants would go ahead of him, removing stones, filling in low places, and straightening curves so the king’s journey would be more pleasant.
Isaiah found in this practice a spiritual principle. The people needed to prepare the way for the coming of the Lord in a new and fresh way-a reference to the future Messiah. In the New Testament, this passage was applied to John the Baptist, who prepared the way for the ministry of Jesus Christ (Luke 3:4-5).
ISAIAH 40:3-4 – Prepare ye the way of the LORD, make straight in the desert a highway for our God . . . . The crooked [rough ground, NIV] shall be made straight [level, NIV], and the rough [rugged, NIV] places plain.