Dr. Martin Luther King, Jr., wasn’t planning to talk about his dream on August 28, 1963. According to pre-eminent civil rights movement historian Taylor Branch in an interview with Meet the Press, King’s original draft was very different than the speech he delivered 50 years ago today. Believe it or not, he extemporaneously added — or basically, ad-libbed — his description of his dream America after being prompted by gospel singer Mahalia Jackson to “Tell them about the dream, Martin.”

Why the unexpected improvisation?

As a good orator, King assessed his audience and felt called to deliver a more inspirational ending to his speech that would best resonate with the 250,000 people who gathered for the March on Washington for Jobs and Freedom, and the millions watching and listening from their homes.

Adjusting your speech to the needs of your audience — even on the fly — without compromising your communication goals will improve your chances of leaving a more lasting, engaging impression with listeners than if you stuck to the original, less relevant script. Can you imagine the civil rights movement or the world today without the “I Have a Dream” rhetoric?

Check out this clip from Branch’s interview with David Gregory to learn more about this pivotal speech and the circumstances that informed King’s choices. To experience King’s speech in a new media way, visit the animated version created by Freedom’s Ring.