If, however, the metals are not fused so that each part is soldered to the other—as in a collar whose two halves are copper and gold—then what results is a mere "mixture-in-separation," which has no right to be called a mixture at all.

It is between these two defective modes that Nestorius and his followers have stumbled. First, they embraced the contrived and corrupting mixture, claiming that the divine nature and the human nature blended in the one Messiah, so that He possesses a single constitution with a single nature compounded of two distinct natures, divine and human. By this they admitted that the two natures had undergone alteration—and alteration is corruption.

On the basis of this unbelieving assertion they fastened calamities and death onto the very nature of God, and reduced the Messiah to something that is neither true God nor true man, just as an alloy of gold and copper is neither genuine gold nor genuine copper.

Then Nestorius and his party adhered to the mixture of division and disjunction, alleging that the one Messiah has two different natures—divine and human—and two well-known entities, one divine and the other human. Thus they treated separation itself as though it were a mixture, like a two-colored collar, one half gold and the other copper, or a padded garment whose outer face is brocade while its lining is cotton: between the two there is no mixture in nature or substance.

On such a premise they have no grounds to believe in a single Messiah, for the two-colored collar is in reality two collars, and the padded garment two separate garments.

Accordingly, the Messiah, in their conception, becomes two: one that is divine in nature and substance—like the gold bar in the bicolored collar or the brocade surface of the padded robe—and another that is human, like the copper bar in that collar or the cotton lining of the robe.