Cur Deus Homo/Book Second/Chapter 2

CHAPTER II
How man would never have died, unless he had sinned.

Anselm. Moreover, it is easily proved that man was so made as not to be necessarily subject to death; for, as we have already said, it is inconsistent with God's wisdom and justice to compel man to suffer death without fault, when he made him holy to enjoy eternal blessedness. It therefore follows that had man never sinned he never would have died.