The "New Negro" as a symbol for hope
Instead of tying the New Negro to a set of rules or behavioral guidelines, Locke offers a true identity to the Black American. By encouraging pride in black culture and heritage, as a folk society, Locke hopes to inspire people to be who they are, instead of trying some new trick that might fool white people into thinking of them as equal. Locke hopes to bring about art that truly changes people's minds.
The "Old Negro" as a symbol for the confusion about the status of black people in society
Instead of talking about the Old Negro as a real entity, Locke wisely calls it the way it is. The "Old Negro" ideology doesn't even dignify black people as people, but rather as abstract ideas or even objects. Locke wants to start from scratch, so instead of talking about the Old Negro as a person, he likens the Old Negro to the failure of the culture to talk successfully about racial reconciliation.
Harlem as an allegory for the kind of revolution Locke would advocate
Locke's central depiction of Harlem as the birthplace of a new, folk-centric identity and culture is one of the most influential aspects of the entire book. The idea that someone could be proud of their culture and heritage was not new, but the idea that art could be their political resistance, that was new. Today, when Kendrick Lamar sings about Compton, there are still echoes of Locke's philosophy there.
Art as political allegory
By pointing out the problems of running against white politicians, and all the spiteful hatred that such attempts would breed, Locke offers a new sense of political involvement, the involvement in the cultural discourse of art. By bringing "New Negro" art into the mainstream, Locke hoped to silently undo the racist ideologies of the people who encountered the art. This was a prerequisite for Locke.
The renaissance as a symbol for cultural exchange
By calling the burgeoning culture of Harlem a "Negro Renaissance," Locke draws attention to the sense of identity that the culture was developing, where they weren't second-class citizens, and the pride of the black culture was inspiring art. For Locke, the Renaissance was the perfect illustration of the kind of cultural rebirth that would have to happen in the arts in order for true social change.