"To be a gentleman—a gentleman without stain or blemish—was his only religion, and to it he was always faithful."

Twain's description of Judge York Leicester Driscoll establishes the importance the Judge places on the code of conduct he has inherited from his ancestors. This code will underpin the conflict between the Judge and his nephew Tom, as well as represent the ongoing push-and-pull dynamic as America expands westward and leaves behind the "Old World" customs of the original colonies.

"But for an unfortunate remark of his, he would no doubt have entered at once upon a successful career at Dawson's Landing. But he made his fateful remark the first day he spent in the village, and it ‘gaged" him.’" 

Twain characterizes the residents of Dawson's Landing as narrow-minded and judgmental. David Wilson's comment about the barking dog seals his fate for two decades as the townspeople, unaccustomed to sarcasm and irony, fail to understand Wilson and characterize him a fool, a "pudd'nhead." 

"To all intents and purposes Roxy was as white as anybody, but the one sixteenth of her which was black outvoted the other fifteen parts and made her a Negro. She was a slave, and salable as such."

Racial identity is a recurring theme in Twain's work, and in this   description of Roxy, Twain emphasizes that the racial categories on which slavery rested were biologically meaningless yet used to absurd and horrific ends.