"It was close place. I took it up, and held it in my hand. 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, Ill go to hell'-and tore it up."
These lines from Chapter 31 describe the moral climax of the novel. The duke and the dauphin have sold Jim, who is being held in the Phelpses’ shed pending his return to his rightful owner. Thinking that life at home in St. Petersburg—even if it means Jim will still be a slave and Huck will be a captive of the Widow— would be better than his current state of peril far from home, Huck composes a letter to Miss Watson, telling her where Jim is. When Huck thinks of his friendship with Jim, however, and realizes that Jim will be sold down the river anyway, he decides to tear up the letter. The logical consequences of Huck’s action, rather than the lessons society has taught him, drive Huck. He decides that going to “hell,” if it means following his gut and not society’s hypocritical and cruel principles, is a better option than going to everyone else’s heaven. This moment of decision represents Huck’s true break with the world around him. At this point, Huck decides to help Jim escape slavery once and for all. Huck also realizes that he does not want to reenter the “sivilized” world: after all his experiences and moral development on the river, he wants to move on to the freedom of the West instead.
http://www.sparknotes.com/lit/huckfinn/quotes.html#explanation3
