She makes such an important point here. This is such a powerful truth when it comes to the United States. A problem isn't deemed worth fixing until it becomes EVERYBODY'S problem; more specifically, in the U.S., it's not deemed a problem worth fixing until it starts affecting white people. And when she writes "and since the evil had been planted, it must pass through certain stages before it could be eradicated", I think she's really highlighting the reality of how slavery and other atrocities are handled in America.Using police brutality as a modern example, such an atrocity won't be addressed as a problem by the government until it passes through certain stages, until it starts to "overshadow important interests." With these few sentences, she really highlights a significant truth that is intrinsic to America.