Gennadius. Lives of Illustrious Men 82

Cyrus, an Alexandrian by race, and a physician by profession, at first a philosopher then a monk, an expert speaker, at first wrote elegantly and powerfully against Nestorius, but afterwards, since he began to inveigh against him too intemperately and dealt in syllogism rather than Scripture, he began to foster the Timothean doctrine. Finally he declined to accept the decree of the council of Chalcedon, and did not think the doctrine that after the incarnation the Son of God comprehended two natures, was to be acquiesced in.