What is the significance of this quote from "American Indian Stories" by Zitkala-Sa?

"...Some missionaries gave me a little bag of marbles. They were all sizes and colors. Among them were some of colored glass. Walking with my mother to the river, on a late winter day, we found great chunks of ice piled all along the bank. The ice on the river was floating in huge pieces. As I stood beside one large block, I noticed for the first time the colors of the rainbow in the crystal ice. Immediately I thought of my glass marbles at home. With my bare fingers I tried to pick out some of the colors, for they seemed so near the surface. But my fingers began to sting with the intense cold, and I had to bite them hard to keep from crying.

From that day on, for many a moon, I believed that glass marbles had river ice inside of them."