6 But this predestination He still more clearly disclosed in respect of His own glorification, wherewith He was glorified by the Father, when He added, “With the glory which I had, before the world was, with You.” The proper order of the words is, “which I had with You before the world was.” To this apply His words, “And now glorify Thou me;” that is to say, as then, so also now: as then, by predestination; so also now, by consummation: do Thou in the world what had already been done with You before the world: do in its own time what You have determined before all times.
This, some have imagined, should be so understood as if the human nature, which was assumed by the Word, were converted into the Word, and the man were changed into God; yea, were we reflecting with some care on the opinions they have advanced, as if the humanity were lost in the Godhead. For no one would go the length of saying that out of such a transmutation of the humanity the Word of God is either doubled or increased, so that either what was one should now be two, or what was less should now be greater. Accordingly, if with His human nature changed and converted into the Word, the Word of God will still be as great as He was, and what He was, where is the humanity, if it is not lost?
Source: Tractates on the Gospel of John (New Advent)