Gennadius. Lives of Illustrious Men 2
2 Julius, bishop of Rome
Julius, bishop of Rome, wrote to one Dionysius a single epistle On the incarnation of Our Lord, which at that time was regarded as useful against those who asserted that, as by incarnation there were two persons in Christ, so also there were two natures, but now this too is regarded as injurious for it nourishes the Eutychian and Timothean heresies.