He lives there above a spick restaurant, and nigger children played naked in the next block among the starving cats, and nigger women sat on the steps […]. (5.147).
Jack sounds terrible here. His racism is mostly manifest in his speech. Yet, he uses the words in anger, almost against themselves. Perhaps this is something that changes for Jack as a result of his encounter with Cass Mastern. We hope so. Language is a powerful tool.
"History is blind, but man is not." (10.438)
This is a quote from Hugh Miller. Jack quotes him near the end of the book. Hugh is suggesting that history is blind because what has happened has happened. History can't see itself. But we can see history. And if we look at it with open eyes there is hope that we can understand it. This speaks directly to the theme of race.