Martin Luther King is a famous historical figure, and he played a very important part in the struggle for equal rights for black people in the United States. He was a superb speaker, and his 'I Have A Dream' speech is perhaps his most celebrated moment.
I have recently been using this speech to show my students how to make their own speech more interesting. Of course, when you first learn a language, you focus on vocabulary and grammar, but when you become more experienced, you can try to use the 'four Ps' - power, pace, pitch, and pause.
In my opinion, the 'I Have A Dream' speech is an absolute masterclass in using the four Ps, as well as being brilliantly written, and hugely politically significant.
Have a look at this video, and listen to the use of power, pace, pitch, and pauses.