Chesnutt's 'The Goophered Grapevine'

In the short story "The Goophered Grapevine" Chesnutt uses the literary technique known as the frame story, in which a first story leads to another story within it by serving as a tool for comparison and contrast between two realities. The story is set in North Carolina shortly after the post-civil war where the first narrator—already engaged in the business of growing grapes—is looking for a place for grape-growing, as shown by these lines:
"I found that grape-culture...was not entirely unknown in the neighborhood...but like most Southern industries, it had felt the blight of war and had fallen into desuetude."
The author's aim is to portray the chasm between the society and mentality of the northern and southern states through two narrating voices: a white northern businessman and a

It must be said that Julius is well aware that there is no spell on the vineyard, but the recourse to magic is a means of dissuading the white businessman from buying a viticulture from which the slave drew a source of income.
"I found, when I bought the vineyard, that Uncle Julius had occupied a cabin on the place for many years, and derived a respectable revenue from the product of the neglected grapevines."
On the one hand, the author describes slaves as not cultured and superstitious people at the mercy of greedy and unscrupulous men like Mars Dugal, but on the other hand, Julius represents a slave who has learned how to prosper by considering the "respectable revenue" he derived from grape-selling.
Although the businessman bought the vineyard, he "paid him for his services as coachman, for" he "gave him employment in that capacity, were more than an equivalent for anything he lost by the sale of the vineyard."
The student has surpassed the master, if I may say