Theandric Operation (θεανδρικὴ ἐνρέγεια), a theological term first used in the 7th century, and intended to express that unity of operation in the two natures and the two wills of our Lord Jesus Christ by which they act as the nature and will of one invisible Person, God and man. It was called a novel term by the Council of Lateran (A.D. 649), and discouraged as such in its 15th canon, which speaks of the "heretics" who had introduced it (τὴν ἐπ᾿ αὐτῆ θεανδρικῇ καινὴν ῥῆσιν), which makes it seem likely that it has been used by some of the Monothelite sect in justification of their principles. John Damascene (De Orthod. Fide, ch. 66) thus explains the term "The Theandric operation, then, signifies this, that when God became man both his human operation was divine, that is, deified, and not void of participation in his divine operation, and his divine operation was not void of participation in his human operation, but either is contemplated in connection with the other. And this manner is styled periphrasis when a person embraces any two things by one expression; for as we call the divided cauterizing and the inflamed incision of a heated knife the same thing, but call the incision one operation and the cauterizing another calling them operations of different natures, the cauterizing of fire and the incision of iron so, also, speaking of one Theandric operation of Christ, we understand of the two natures to be two-the divine that of his-divinity, and the human that of his humanity."