metaphor
a figure of speech that is used to make a comparison between two things that aren't similar, but they have some characteristics in common.
A example would be You are a light of my life (it doesn't mean that something is literary light to someone, no one can provide physical light. This metaphor means that someone brings happiness to another one).
it creates an image of how miserable Negro men and women were, how they endured their hard lives, so that decided to rise in a protest. The mood is tense at first, then it creates an uplifting mood, full of strength to fight the injustice.
use of these metaphors helped a writer to depict creatively and interestingly about the feelings and life of men and women. It helped to create a strong image in the readers