"Jim was most ruined for a servant, because he got stuck up on account of having seen the devil and been rode by witches."
Chapter 2. Here, slaves are portrayed as ignorant and superstitious creatures.
"I do believe he cared just as much for his people as white folks does for their'n." Chapter 23. Huck is speaking of Jim, and marvelling at the fact that Jim is just like anyone else--he thinks, feels, and hopes. The only difference is his skin color.
"I was a-trembling, because I'd got to decide, forever, betwixt two things, and I knowed it. I studied a minute, sort of holding my breath, and then says to myself: 'All right, then, I'll GO to hell.'" Chapter 30. Huck has been fighting with himself regarding his upbringing and teaching about slaves being property and his first-hand knowledge and new friendship with Jim as a person, not just a slave. Huck has been struggling with turning in Mrs. Douglas' property or letting his friend go free to seek his fortune.
"I know what you'll say. You'll say it's dirty Low-down business; but what if it is? - I'm low down; and I'm agoing to steal him, and I want you to keep mum and not let on. Will you?"
Chapter 33. Here, Huck is explaining to Tom that Jim has been sold and that Huck intends to steal him from these people to set him free. Huck knows Tom will still support the ideology they have been taught regarding slaves while Huck has learned differently.