Infirmity's Purpose?

The “condition of being actually defenseless may perhaps reveal to these people certain actualities of our human existence, in which we are in fact basically defenseless, more clearly than can ever be possible for those of us who are healthy.”  Dietrich Bonhoeffer

And he said unto me, My grace is sufficient for thee: for my strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me.  2 Corinthians 12:9