Cf. Serm. LXX. chap. 3, nisi enim Verbum caro fieret, et tam solida consisteret unitas in utraque natura, ut a suscipiente susceptam nec ipsum breve mortis tempus abiungeret, nunquam valeret ad æternitatem redire mortalitas. Bright (n. 96) quotes authorities ancient and more recent to show that this has always been the Christian’s belief.