Wilkerson posits that the race-based unspoken social rules in America are analogous to a caste system like the one in India, and also pitilessly demonstrates how Nazi Germany formed their own systems of categorizing people based on what they learned of the US. There are oh so many details in this book (and it’s another one which I intend to buy later, so I can mark it up and drink it in properly) but my best takeaway from this book is that if you look at racism in the US from the viewpoint of a caste system, then it makes total sense that people doing racist things don’t see themselves as racist; the word “racist” implies a person who is acting outside the bounds of civil behavior, whereas since the entire foundation of American civil society is bounded and defined by racism, those steeped in that culture will justify any actions taken in upholding that system. With patient, inexorable detail, Wilkerson uncovers the pillars supporting the caste system, and provides many examples of how it hurts all Americans, not just the ones at the bottom.