"The reason of the close concurrence between the individual's progress and that of the race appears, therefore, when we remember the dependence of each upon the other"

James M. Baldwin is mentioning the close connection between an individual's progress which of their race. He discusses that this connection ends up being clear when we keep in mind that each individual is dependent on their race, and vice versa. This implies that the development of the individual is carefully linked to the development of their race, and that one can not be accomplished without the other. Baldwin's quote recommends that individuals have a responsibility towards their race, as any progress they make is likely to benefit their entire neighborhood. In essence, the success of the person is inherently tied to the success of their race as a whole.