The plain meaning therefore is, that the Speech begotten by God before all ages, and who always dwelt with the Father, was made man. On this article there are two things chiefly to be observed. The first is, that two natures were so united in one Person in Christ, that one and the same Christ is true God and true man. The second is, that the unity of person does not hinder the two natures from remaining distinct, so that his Divinity retains all that is peculiar to itself, and his humanity holds separately whatever belongs to it. And, therefore, as Satan has made a variety of foolish attempts to overturn sound doctrine by heretics, he has always brought forward one or another of these two errors; either that he was the Son of God and the Son of man in so confused a manner, that neither his Divinity remained entire, nor did he wear the true nature of man; or that he was clothed with flesh, so as to be as it were double, and to have two separate persons.
–John Calvin (1509-1564)