“Crazy Horse dreamed and went into the world where there is nothing but the spirits of all things. That is the real world that is behind this one, and everything we see here is something like a shadow from that one.”

Black Elk Speaks (1961)
Context: Crazy Horse dreamed and went into the world where there is nothing but the spirits of all things. That is the real world that is behind this one, and everything we see here is something like a shadow from that one. He was on his horse in that world, and the horse and himself on it and the trees and the grass and the stones and everything were made of spirit, and nothing was hard, and everything seemed to float. His horse was standing still there, and yet it danced around like a horse made only of shadow, and that is how he got his name, which does not mean that his horse was crazy or wild, but that in his vision it danced around in that queer way.
It was this vision that gave him his great power, for when he went into a fight, he had only to think of that world to be in it again, so that he could go through anything and not be hurt. Until he was killed at the Soldiers' Town on White River, he was wounded only twice, once by accident and both times by some one of his own people when he was not expecting trouble and was not thinking; never by an enemy. He was fifteen years old when he was wounded by accident; and the other time was when he was a young man and another man was jealous of him because the man's wife liked Crazy Horse.
They used to say that he carried a sacred stone with him, like one he had seen in some vision, and that when he was in danger, the stone always got heavy and protected him somehow. That, they used to say, was the reason that no horse he ever rode lasted very long. I do not know about this; maybe people only thought it; but it is a fact that he never kept one horse long. They wore out. I think it was only the power of his great vision that made him great.