Paul Helm has posted an excellent piece on the incarnation here. He begins with this wonderful quote from Augustine:
Wherefore the Word of God, who is also the Son of God, co-eternal with the Father, the Power and the Wisdom of God, mightily pervading and harmoniously ordering all things, from the highest limit of the intelligent to the lowest limit of the material creation, revealed and concealed, nowhere confined, nowhere divided, nowhere distended, but without dimensions, everywhere present in His entirety, — this Word of God, I say, took to Himself, in a manner entirely different from that in which He is present to other creatures, the soul and body of a man, and made, by the union of Himself therewith, the one person Jesus Christ,
Mediator between God and men, he His Deity equal with the Father, in His flesh, i.e. in His human nature, inferior to the Father, — unchangeably immortal in respect of the divine nature, in which He is equal with the Father, and yet changeable and mortal in respect of the infirmity which was His through participation with our nature.
Augustine, Letter to Volusian, (Letter 137)
Do read the whole of Professor Helm’s article.