46 And so let us see for what ways of God, and for what works of God, Wisdom was created from the commencement of the ages, though born of God before all ages. Adam heard the voice of One walking in Paradise. Do you think that His approach could have been heard, had He not assumed the guise of a created being? Is not the fact, that He was heard as He walked, proof that He was present in a created form? I do not ask in what guise He spoke to Cain and Abel and Noah, and in what guise He was near to Enoch also, blessing him.
An Angel speaks to Hagar, and certainly He is also God. Has He the same form, when He appears like an Angel, as He has in that nature, by virtue of which He is God? Certainly the form of an Angel is revealed, where afterwards mention is made of the nature of God. But why should I speak of an Angel? He comes as a man to Abraham. Under the guise of a man, in the shape of that created being, is not Christ present in that nature, which He possesses as being also God? A man speaks, and is present in the body, and is nourished by food; and yet God is adored.
Surely He Who was an Angel is now also man, in order to save us from the assumption that any of these diverse aspects of one state, that of the creature, is His natural form as God. Again, He comes to Jacob in human shape, and even grasps him for wrestling; and He takes hold with His hands, and struggles with His limbs, and bends His flanks, and adopts every movement and gesture of ours. But again He is revealed, this time to Moses, and as a fire; in order that you might learn to believe that this created nature was to provide Him with an outward guise, not to embody the reality of His nature.
He possessed, at that moment, the power of burning, but He did not assume the destructive property which is inherent in the nature of fire, for the fire evidently burned and yet the bush was not injured.
Source: On the Trinity (New Advent)