The voice of him that cries in the wilderness, Prepare you the way of the LORD, make straight in the desert a highway for our God.
All Commentaries on Isaiah 40:3 Go To Isaiah 40
Tertullian of Carthage
AD 220
Since even then by Isaiah it was Christ, the Word and the Spirit of the Creator who prophetically described John as “the voice of one crying in the wilderness to prepare the way of the Lord.” And [he] was about to come forth for the purpose of terminating from that point onwards the course of the law and the prophets: by their fulfillment and not their extinction.