> and that there's nothing left to challenge. Also, I would add that history is not linear, it’s not the progressive challenging of old prejudices. Sometimes,

> and that there's nothing left to challenge. Also, I would add that history is not linear, it’s not the progressive challenging of old prejudices. Sometimes, in our efforts to strive for better morals, we make terrible mistakes. Phrenology come to mind, but there could be many other examples.