I edited your question slightly for it to make more sense, as your previous question was slightly unclear. I hope I have still captured the essence of what you wanted to ask! This famous poem by Langston Hughes concerns the fate and plight of African Americans suffering severe poverty during the Depression in America. Hughes works hard to create a pervading mood of oppression that is captured by describing Harlem as standing on "the edge of hell." The memories of oppression are captured by referring to the "old lies" and the reference to remembering. However, perhaps crucially, there is a distinct shift in tone in the last stanza. Let us consider this part of the poem in detail:

So we stand here
On the edge of hell
In Harlem
And look out on the world
And wonder
What we're gonna do
in the fact of what
We remember.

Note how the mood of oppression that comes through clearly at the beginning of the poem subtly transforms into a mood of possible revolt or protest, as the residents of Harlem consider the world, or "look out on the world," pondering their response to the injustice and oppression they have experienced and are experiencing. The repeated reference made to "remembering" seems to be the catalyst of this feeling; it is what they "remember" that gives the last stanza its angry, forceful and indignant tone.