The Angel of YHWH an OT Enigma

Commenting on the appearance of "the angel of YHWH" in Exodus 3, D. A. Carson asks and oberves:

We might well ask if, when the text before us records that "God said," it really means no more than that God spoke through this angelic messenger: after all, if the messenger speaks the words of God, then in a sense it is God himself who is speaking. But the biblical manifestations of "the angel of the LORD" do not easily fit into so neat and simplistic an explanation. It is almost as if the biblical writers want to stipulate that God himself appeared, while distancing this transcendent God from any mere appearance. The angel of the Lord remains an enigmatic figure who is identified with God, yet separable from him—an early announcement, as it were, of the eternal Word who became flesh, simultaneously God's own fellow and God's own self (John 1:1, 14).

 —For the Love of God, Vol. 1 (Wheaton: Crossway, 1998), February 20.