Running out of raw material

From Reaching for the Invisible God:

Here, Yancy quotes Paul Tournier. Who, from what I can gather was a Swiss physician turned Christian psychotherapist. He lived mostly during the first half of the last century.

The most wonderful thing in this world is not the good that we accomplish, but the fact that good can come out of the evil that we do. I have been struck, for example, by the numbers of people who have been brought back to God under the influence of a person to whom they have had some imperfect attachment… Our vocation is, I believe, to build good out of evil. For if we try to build good out of good, we are in danger of running out of raw material.

I see this now goes to reinforce one of the major points he established earlier in the book:

The world is good.
The world is fallen.
The world can be redeemed.

Yancy calls this the story of the universe. I can’t help but think I’ve seen this same idea in other places, but worded differently.