Synusiastme (συνουσιασταί) were those who held that the incarnation of our Lord was effected by a blending or commixture of the Divine substance with the substance of the human flesh. The name is taken from the statement of the doctrine συνουσίωσιν γεγενῆσθαι καὶ κρᾶσιν τῆς θεότητος (Theod. Her. Fab. 4:9). Theodoret calls this sect Polemians, one of the Apollinarist sects; and Apollinaris himself, in the latter part of his life, added to his distinguishing heresy regarding the soul of our Lord either this heresy or one closely akin to it. At the Lateran Council in A.D. 649 were quoted two extracts from Polemon's works, from which it appears that the Synusiastue retained the heresy regarding the soul of our Lord, denying him a human will, and asserting that he was to himself a rational soul. They seem to have been led to the adoption of the heresy in this manner. At the outbreak of the controversies regarding. the incarnation, some asserted the conversion of the substance of the Godhead into the substance of flesh, others that the Divine nature supplied in Christ the place of the human soul. The attempt to hold these two tenets together resulted in a denial of an ἐνανθρώπησις altogether. To avoid this denial, it was allowed that the flesh of man was assumed, but so blended with the Divine substance as to eliminate that tendency to sin which it was alleged could not but be resident in human nature. Diodorus of Tarsus and Theodotus of Antioch wrote against this heresy. See Cave, Hist. Lit.; Blunt, Dict. of Sects, etc., s.v.