Was the Old Law given through the mediation of angels or was it given directly by God?

It seems that the Old Law was given directly (immediate) by God and not through the mediation of angels (per angelos):

Objection 1:  Angel means messenger, and so the name ‘angel’ implies ministry and not dominion—this according to Psalm 102:20ff. (“Bless the Lord, all you His angels ..... His ministers (ministri)”).  But the Old Law is said to have been given by the Lord; for Exodus 20:1 says, “The Lord spoke these words .....” and later adds, “For I am the Lord your God.”  And this same manner of speaking is frequently repeated in Exodus and in the succeeding books of the Law.  Therefore, the Law was given directly by God.

Objection 2:  As John 1:17 says, “The Law was given by Moses.”  But Moses received it directly from God; for Exodus 33:11 says, “The Lord spoke to Moses face to face, as a man is wont to speak to his friend.”  Therefore, the Old Law was given directly by God.

Objection 3:  As was explained above (q. 90, a. 3), it is the role of the ruler alone to make law.  But God alone is the ruler of the salvation of souls, whereas the angels are “ministering spirits,” as Hebrews 1:14 puts it.  Therefore, since the Old Law was ordered toward the salvation of souls, it was inappropriate for it to be given through the mediation of angels.

But contrary to this:  In Galatians 3:19 the Apostle says, “The Law was given through the angels at the hand of a Mediator.”  Again, in Acts 7:53 Stephen says, “You have received the Law under the direction of angels.”

I respond:  The Law was given by God through the mediation of angels.  In addition to the general reason that Dionysius gives in De Caelesti Hierarchia, chap. 4, viz., that “it is appropriate for divine realities to be brought to men by the mediation of angels,” there is a special reason why the Old Law had to be given through the mediation of angels.
For it was explained above (a. 1‑2) that the Old Law was imperfect and yet disposed men for the perfect salvation of the human race that was going to come about through Christ.  But it is evident in the case of all ordered powers and crafts that the one who ranks higher performs the principal and perfect act by himself, whereas it is through the mediation of his helpers (per suos ministros) that he does the things that dispose [the patient] for the ultimate perfection.  For instance, a ship‑builder puts the ship together by himself, but he prepares the materials through the mediation of the assistant craftsmen.
So it was fitting that (a) the perfect law of the New Covenant should be given directly by God Himself made man, but that (b) the Old Law should be given to men through the mediation of God’s ministers, viz., the angels.  And it is in this way that the Apostle, at the beginning of Hebrews, establishes the preeminence of the New Law over the Old Law; for in the New Testament God “has spoken to us in His own Son,” whereas in the Old Testament “His word was given through the angels.”

Reply to objection 1:  As Gregory notes at the beginning of Moralia, “The angel who is described as having appeared to Moses is variously called ‘the angel’ and ‘the Lord’.  He is called ‘the angel’ by reason of the fact that he served by speaking exteriorly, whereas he is called ‘the Lord’ because, presiding interiorly, he administered the power of speaking.”  Hence, the angel was also, as it were, speaking in the person of the Lord.

Reply to objection 2:  As Augustine points out in Super Genesim ad Litteram 12, Exodus 33:11 says, “The Lord spoke to Moses face to face,” and a little later adds, “Show me Your glory.”  Therefore, Moses was sensing what he saw and desiring what he did not see.  Therefore, he did not see the very essence of God, and in this sense he was not directly instructed by God.
Therefore, when Scripture says, “He spoke to him “face to face,” it speaking in accord with the opinion of the people, who thought that Moses and God were speaking with their mouths, because God was speaking to him and appearing to him through creatures subject to Him, i.e., through the angel and through the cloud.
An alternative reply is that “seeing God’s face” refers to a certain preeminent and intimate contemplation that falls short of the vision of God’s essence.

Reply to objection 3:  It is the role of the ruler alone to institute law by his own authority, but he sometimes promulgates an instituted law through others.  And so God instituted the Law by His own authority, but He promulgated it through the angels.