Just as the skin color of human beings is changeable, as evidenced by the success of Dr. Crookman’s Black-No-More treatment, so is the human heart and the human capacity for reason. This mutability over time is a prominent theme of the novel; at times, the changeable nature of people can work positively, and other times, it has a negative impact on individuals and society.

Helen’s change of heart is an example of the potential for the mutability of human nature to be positive. At the start of the novel, Helen is coldly hostile and dismissive of black people, specifically Max; later descriptions reveal that Helen is a product of her home environment, where her parents, Rev. Givens and Mrs. Givens, cultivated her most superficial qualities and indulged her reluctance to become educated. When Matthew reveals to Helen that he is the reason their baby is born with darker skin than she expected, Helen’s reaction is positive; she has just learned that she herself is of mixed blood, so she accepts Matthew’s confession, and their baby boy, immediately and with some semblance of tenderness. 

The reaction of the residents of Happy Hill, Mississippi to the appearance of Dr.