There are many encounters that believers have had with God in the Old Testament, the explanations of which (how men could meet with God and live) was a problem for Jewish scholars, who, instead, attributed these incidents to men meeting with God's Wisdom/Logos/Word personified. Of course they could not explain further, at the risk of contradicting monotheism, preferring, instead, to remain silent.
Jesus, God's Wisdom, and the Trinity
This conception of Wisdom parallels a less significant, general
Jewish explanation of how a transcendent God could participate in a
temporal creation. The Aramaic Targums resolved this problem by
equating God with His Word; thus, in the Targums, Exodus 19:17, rather
than saying the people went out to meet God, it says that the people
went out to meet the word of God, or Memra.
This term became a periphrasis for God; whether it could have been
reckoned as a separate person, as in Christian Trinitarianism, is a
matter of debate. The risk involved with making Wisdom/Word an
independent deity was too great for the rabbis to speculate further,
but Christians found in the Wisdom tradition an ideal categorical
conception within which to place the person of Jesus.
One more verse about angels mediating the Law:
Galatians 3:19Why the Law then? It was added because of transgressions, having been ordained through angels by the agency of a mediator, until the seed would come to whom the promise had been made.