The speech is also important in relation to W.E.B. DuBois's concept of "double-consciousness"—that is, having one's own sense of identity but also being obligated to behave according to the expectations of white supremacy. The narrator's grandfather encourages him to placate white people, to behave according to their expectations. Both the narrator and the grandfather know that this obsequious behavior is a ruse.
What is ironic about the speech is that the narrator's grandfather believes that the maintenance of this ruse is a part of "the good fight." The "fight," in other words, is the will to survive in a system that is bent on killing black men. Thus, the narrator's grandfather is telling him to satisfy white expectations, however demeaning, so that he can live.
The grandfather implies that he has been complicit in a system that has attempted to diminish his manhood. When he states that he has been "a spy in the enemy's country" ever since he put down his gun during Reconstruction, he offers a statement not only on losing the fight for full enfranchisement but also on losing out on the possibility to be regarded as an equal man. A gun is a symbol of masculine power and is sometimes regarded as a phallic symbol. Black men who asserted their masculinity, or any individual pride, were often lynched in the South.
The grandfather feels like "a spy" because he must observe white people constantly, knowing them better than they know themselves. In this way, he can anticipate their moods and actions for his own benefit. He feels that he's "in the enemy's country" because he must exist in a land that is bent on his destruction. Thus, he is at war, but it isn't a conflict in which he can assert his power directly.
The speech is important because it reveals the complex nature of being black in American society—even today. Black people who wish to acquire status or economic power within American society must make certain compromises, which may include being demeaned or insulted on account of one's race. They must then pretend not to be impacted by this, or perhaps not even to mind. This complicity with one's own oppression is reflected in the grandfather's direction to "overcome 'em with yeses" and "undermine 'em with grins." The narrator's grandfather presents the existential problem that has been central to black people's lives in the United States: should one compromise one's dignity and selfhood in order to live?