If you understand this, then perhaps the single steps of the Christological doctrine are easy to understand. Always have two pictures in your mind if you want to understand them: 1) The being with the two heads, where there is no unity: God and man.
2) The being in which one head has disappeared, but also humanity has disappeared.
The one head is the head of the Logos, of God Himself, so that when Jesus acts it is not the unity of something human and something Divine, but-it is something else: it is the Logos who acts. So all the struggles, all the uncertainties, the despairs, the loneliness, and all this which we have in the Gospel picture, is only seemingly and not really so. It has no consequences: it is inconsequential. This was the danger of the Eastern development, and the fact that this danger has been overcome is the great importance of the decision of Chalcedon, for which we must be very grateful to the Eastern church that it was able to do this against its own basic feeling. But the power of the Old Testament and the power of the full picture of the human side in Jesus, was such that the East couldn’t fail in this respect.
I come now to one of the most interesting figures in Eastern church history,Dionysius the Areopagite (Pseudo-Dionysius), who was also of extreme importancefor the West. (Cf. Acts 17:34, where a man called Dionysius followed Paul who was speaking in the Areopagus; he is called Dionysius the Areopagite, in the tradition. His name was used by a ‘writer writing between 480-510, probably ca. 500.