Here’s a working thesis with potential: you have highlighted an important aspect of the novel for investigation. However, it’s still not clear what your analysis will reveal. Your reader is intrigued but is still thinking, “So what? What’s the point of this contrast? What does it signify?” Perhaps you are not sure yet, either. That’s fine—begin to work on comparing scenes from the book and see what you discover. Free write, make lists, jot down Huck’s actions and reactions. Eventually you will be able to clarify for yourself, and then for the reader, why this contrast matters. After examining the evidence and considering your own insights, you write:
" Thesis . This advanced exercise [one of the progymnasmata ] asks the student to write an answer to a 'general question' ( quaestio infina )--that is, a question not involving individuals. . Quintilian . . notes that a general question can be made into a persuasive subject if names are added (). That is, a Thesis would would pose a general question such as 'Should a man marry?' or 'Should one fortify a city?' (A Special Question on the other hand would be 'Should Marcus marry Livia?' or 'Should Athens spend money to build a defensive wall?')"
(James J. Murphy, A Short History of Writing Instruction: From Ancient Greece to Modern America , 2nd ed. Lawrence Erlbaum, 2001)