Sioux healer Black Elk told John Neihardt (1932, Chapter 18):
… many I cured with the power that came through me. Of course it was not I who cured. It was the power from the outer world, and the visions and ceremonies had only made me like a hole through which the power could come to the two-leggeds. If I thought that I was doing it myself, the hole would close up and no power could come through. Then everything I could do would be foolish.
Later in the same chapter:
It is from understanding that power comes; and the power in the ceremony was in understanding what it meant; for nothing can live well except in a manner that is suited to the way the sacred Power of the World lives and moves.