Could you hand me the remote? Could you pass the chips? Could you turn up the volume? Could you scoot over? Could you not chew with your mouth open?

Could you stop?

We're all familiar with anaphora (above, in the annoying mode). In this rhetorical device, exact sequences of words repeat in several sentences.

Check out Paragraph 6, where MLK repeats the phrase "Now is the time" in four straight sentences. The purpose here is to make a particular idea or theme stick in the audience's memory. In this case, he's attempting to make an argument for the urgency of getting change done now:

We have also come to this hallowed spot to remind America of the fierce urgency of now. This is no time to engage in the luxury of cooling off or to take the tranquilizing drug of gradualism. Now is the time to make real the promises of democracy. Now is the time to rise from the dark and desolate valley of segregation to the sunlit path of racial justice. Now is the time to lift our nation from the quicksands of racial injustice to the solid rock of brotherhood. Now is the time to make justice a reality for all of God's children. (6)

Martin Luther King, Jr. uses anaphora to great effect at the end of his speech, when he talks about faith:

With this faith we will be able to hew out of the mountain of despair a stone of hope. With this faith we will be able to transform the jangling discords of our nation into a beautiful symphony of brotherhood. With this faith we will be able to work together, to pray together, to struggle together, to go to jail together, to stand up for freedom together. (18.3-5)

The repetition of the specific words "with this faith" holds together some long and winding sentences, helping the audience follow along.

Another example, this time from the beginning of the speech: King repeats the phrase "one hundred years later" in Paragraph 3, describing how things are for African Americans long after the Emancipation Proclamation (3.2-4). This drives home the message that progress has been slow over a very long time, which is depressing or hopeful, depending on whether you're a glass half-full or glass half-empty person.

Fifty-three years later (see what we did there?), this speech still works wonders in the minds of listeners. Seriously, listen to this speech on Youtube. The effect of anaphora will pretty much explain itself.