The most poignant and important moment in the text presents an emotional appeal. Huck finds himself at a cross-roads of conscience when Jim has been sold by the King and the Duke for forty dollars to the Phelps family.
At this point in the narrative, Huck finds himself alone. His isolation is not merely social, however, as he has now come to the crisis point in his larger effort to come to terms with the morality of society. This is the central conflict of the novel.
Huck, in this moment, grapples with a deeply felt guilt as he weighs his friendship with Jim against the dictates of his society. He feels he will be condemned to hell if he chooses to help Jim escape from bondage (because Jim is technically property). Stealing is a sin, for Huck, because it is a crime.
However, Huck cannot overcome the more pressing moral ideal that friendship presents. In this critical moment, Huck's emotional turmoil is fully articulated in Twain's writing. Huck engages with his moral dilemma directly and comes to the point where he says he will "go to hell" if he has to in order to save Jim.
This emotional moment appeals to the reader's sense of sympathy for Huck and draws out Huck's moral challenge so that it becomes, finally, intertwined with his emotional well-being.