Why might Obama have quoted the Constitution at the beginning of his speech?

      "Obama highlighted the tension between the ideals of equal citizenship and freedom expressed in the Constitution and America's history of slavery, and connected the American Civil War and civil rights movement with the goals of his own campaign, "to continue the long march of those who came before us, a march for a more just, more equal, more free, more caring and more prosperous America."

Explanation:

Brainliest?

answer; the period of time known as the middle ages;