Why does Stowe use this? What does it reveal about hayley? How does it serve as an indictment of the economy of slavery?

It really shows the depravity that man can stoop to when he looses his conscience, when he lets evil take hold of his heart. The economy of slavery turns people into commodities. Hayley is the worst kind of slave trader. He mixes freely with other evil traders as well as the reprehensible trackers who hunt slaves down.