St John of Damascus on Ἐνέργεια Θεανδρική

St John of Damascus

"When the blessed Dionysius said that Christ had used a certain new theandric operation with us [Epistle IV], he was not doing away with the natural operations and saying that there was one operation proceeding from the human and divine natures.  For, if such were the case, we might also say that there was one new nature made from the human and the divine, because, according to the holy Fathers, things which have one operation also have one substance.  on the contrary, he wanted to show that the new and ineffable manner of the manifestation of the natural operations in Christ was consonant with the mutual indwelling of Christ's natures in each other, and that His living as a man was both unusual and incredible and unknown to the nature of things.  He also wanted to show the manner of the exchange arising from the ineffable union.  Thus, we do not say that the operations are separated and that the natures act separately, but we say that they act conjointly, with each nature doing in communion with the other that which it has proper to itself.  He did not perform the human actions in a human way, because He was not a mere man, nor did He perform the divine actions in a divine way only, because He was not just God, but God and man together.  And just as we understand both the union of the natures and their natural difference, so also do we understand that of the natural wills and operations.

"So that one must know that while we sometimes speak as of two natures in our Lord Jesus Christ, we sometimes speak as of one person, and that both the former way of speaking and the latter refer to the same concept.  For the two natures are one Christ and the one Christ is two natures.  It is therefore the same thing to say that Christ acts according to each of His natures and to say that each nature in Christ acts in association with the other.  Accordingly, when the flesh id acting, the divine nature is associated with it because the flesh is being permitted by the good pleasure of the divine will to suffer and do what is proper to it and because the operation of the flesh is absolutely salutary--which las does not belong to the human operation, but to the divine.  And when the divinity of the Word is acting, the flesh is associated with it, because the divine operations are being performed by the flesh as by an instrument and because He who is acting at once in a divine and human way is one.

"One should furthermore know that His sacred mind performs His natural operations, both understanding and knowing itself to be the mind of God and adored by all creation, but at the same time still mindful of His doings and sufferings on earth.  It is, moreover, associated with the operation of the divinity of the Word by which the universe is ordered and controlled, understanding and knowing and ordering not as a mere human mind, but as one hypostatically united to God and reckoned as the mind of God.

"Thus, the theandric operation shows this:  when God became man, that is to say, was incarnate, His human operation was divine, that is to say, deified.  And it was not excluded from His divine operation, nor was His divine operation excluded from His human operation.  On the contrary, each is found with the other.  Now when one expresses two things with one word, this figure of speech is called circumlocution [περίφασις].  Thus, while we speak of the cut burn and the burnt cut of the red-hot knife, we nevertheless hold the cutting to be one operation and the burning another, the one belonging to one nature and the other to the other--the burning to the fire and the cutting to the steel.  In the very same way, when we speak of one theandric operation of Christ, we understand the two operations of His two natures:  the divine operation of the divinity and the human operation of the humanity."

St John of Damascus,
de fide Orthodoxa, III.19