Cur Deus Homo/Book Second/Chapter 4

CHAPTER IV
How God will complete, in respect to human nature, what he has begun.

Anselm. From these things, we can easily see that God will either complete what he has begun with regard to human nature, or else he has made to no end so lofty a nature, capable of so great good. Now if it be understood that God has made nothing more valuable than rational existence capable of enjoying him; it is altogether foreign from his character to suppose that he will suffer that rational existence utterly to perish.

Boso. No reasonable being can think otherwise.

Anselm. Therefore is it necessary for him to perfect in human nature what he has begun. But this, as we have already said, cannot be accomplished save by a complete expiation of sin, which no sinner can effect for himself.

Boso. I now understand it to be necessary for God to complete what he has begun, lest there be an unseemly falling off from his design.