As the story goes, Mahalia Jackson called out, “Tell them about your dream, Martin! Tell them about the dream!” — From the U.S. Department of State web site –

Dr. Martin Luther King Jr. had originally prepared a short and somewhat formal recitation of the sufferings of African Americans attempting to realize their freedom in a society chained by discrimination. He was about to sit down when gospel singer Mahalia Jackson called out, “Tell them about your dream, Martin! Tell them about the dream!” Encouraged by shouts from the audience, King drew upon some of his past talks, and the result became the landmark statement of civil rights in America — a dream of all people, of all races and colors and backgrounds, sharing in an America marked by freedom and democracy.

That something so amzing was impromtu — ad-libbed — amazing…