Final answer:
The literary device exemplified in the quote by W.E.B. Du Bois is rhetorical questioning, which emphasizes the power of the vote and the potential for change it represents.
Step-by-step explanation:
The literary device exemplified in the quote from Chapter 1: "Of Our Spiritual Strivings" by W.E.B. Du Bois is rhetorical questioning. Rhetorical questions are those that do not require an answer because they are used to emphasize a point or provoke thought. In this context, Du Bois employs rhetorical questions to stress the power and potential of the vote, reflecting on its history of effecting enormous change, such as waging war and emancipating slaves. By questioning the limits of what can be achieved through voting, the author highlights both the importance of political engagement and the empowerment that constitutional amendments like the Fifteenth Amendment bestowed upon the newly freed African Americans.