I just discovered this article. I have always loved his writing, particularly Huckleberry Finn. Here his growing awareness of his own racism is discussed, among other things. He has some great quotes. Here's an example:
Patriotism “is a word which always commemorates a robbery. There isn’t a foot of land in the world which doesn’t represent the ousting and re-ousting of a long line of successive ‘owners’ who each in turn, as ‘patriots,’ with proud swelling hearts defended it against the next gang of ‘robbers’ who came to steal it and did—and became swelling-hearted patriots in their turn.”