Throughout the story, Huck is in moral conflict with the received values of the society in which he lives, and while he is unable to consciously refute those values even in his thoughts, he makes a moral choice based on his own valuation of Jim's friendship and Jim's human worth, a decision in direct opposition to the things he has been taught. Mark Twain, in his lecture notes, proposes that "a sound heart is a surer guide than an ill-trained conscience" and goes on to describe the novel as "...a book of mine where a sound heart and a deformed conscience come into collision and conscience suffers defeat". 
Adventures of Huckleberry Finn was unique at the time of its publication (1884) because it is narrated by Huck himself and is written in the numerous dialects common in the area and time in which the book is set. Although the book was originally intended as a sequel to the children’s book The Adventures of Tom Sawyer , as Twain wrote Adventures of Huckleberry Finn it progressed into a more serious work. Twain’s views on slavery and other social issues of the time become clear through the words, thoughts, and actions of Huck Finn. The book has always been the subject of great controversy, and according to The American Library Association it was fifth on the list of most frequently challenged books in the 1990s.
(Summary by Annie Coleman)