At the end of the Old Testament we find a sense of thankfulness and anticipation that the God of Israel not only had called Israel out and blessed her, but the there would be a time of transition when He would reveal His Messiah
Malachi 3:1; John 1:16-18
1. The distinction between the "messenger" who prepares the way and the "Messenger of the Covenant".
2. The coming of Messiah/Messanger was a "dawning", made aware by the "messenger" preparing the way.