" Instead, he began to preach. Mahalia Jackson, behind him on the platform, called out “Tell ’em about the dream, Martin.” He paused, for an instant. “I still have a dream,” he said. “It is a dream deeply rooted in the American dream. I have a dream that one day this nation will rise up and live out the true meaning of its creed: ‘We hold these truths to be self-evident, that all men are created equal.’” He found his rhythm, and the depth of his voice, and the spirit of Scripture. “I have a dream today,” he said, shaking his head. “I have a dream that one day every valley shall be exalted.” The crowd rose, and bowed their heads, and wept. “Let freedom ring!” he cried.47 It was as if every bell in every tower in every city and town and village had rung: a toll of justice. "

― Jill Lepore , These Truths: A History of the United States