On 28 August 1963, at the Lincoln Memorial, Martin Luther King Jr. departed from his prepared text. Mahalia Jackson, standing behind him, is reported to have called out: Tell them about the dream, Martin. What followed was largely extemporized from material he had used before, and it is the most studied passage of English oratory of the twentieth century.
Its structure is almost entirely repetition. I have a dream, eight times, each launching a new image. Let freedom ring, ten times, each attached to a different mountain. Now is the time, four times. Earlier, the banking metaphor of the promissory note returned to and elaborated. These are classical figures — anaphora, the repetition of an opening phrase; epistrophe, repetition at the end; auxesis, arrangement in ascending intensity — and King, a preacher in a tradition built on them, deployed them with complete command.
The question for a guide about influence is why the form itself moves people, independent of the content.
Two mechanisms are reasonably well supported.
The first is synchrony. Robin Dunbar's research group has found that synchronized activity — singing together, rowing together, dancing together — raises pain thresholds, an accepted proxy for endorphin release, and increases feelings of social bonding, with effects beyond what the activity alone produces. Rhythmic speech with call-and-response entrains an audience: breathing aligns, the crowd responds at predictable points, and thousands of people are doing the same thing at the same time. The bonding produced is real and physiological, and it attaches to whoever is at the front.
The second is prediction. Repetition with variation sets up an expectation and then fulfills it. Work by Valorie Salimpoor, Robert Zatorre and colleagues on music has found dopaminergic activity during the anticipation of a musical peak as well as at the peak itself, with the anticipation phase engaging the reward system. A rhetorical cadence is a prediction structure: after the third I have a dream, the audience knows the fourth is coming, and the fulfillment carries a small reward that has nothing to do with the proposition being asserted.
Which is the uncomfortable part, and the reason this chapter belongs in this part of the guide rather than in a section on great speeches.
The form is content-neutral. The same devices, the same entrainment, the same anticipation-and-fulfillment structure, work identically in the service of anything. Nuremberg used them. Every demagogue in Part 7 of this guide used them. The physiological bonding a crowd feels while responding in unison is not evidence about what it is responding to, and it will be experienced as conviction.
This is not an argument against rhetoric, and it is certainly not an argument against the speech at the Lincoln Memorial, which was true as well as beautiful. It is an argument for separating two judgments that the form is designed to fuse: whether this moved me, and whether this is right.
The practical version is the one from chapter 44. Read the transcript, alone, in silence, some time later. Everything that survives that is argument. What does not survive was cadence, and cadence is available to anyone.
Cross-ref: illusory truth via repetition