Sam Leith considers the components of a good speech:
It must be forceful in argument, memorable in style, resonant in its references. It must also, before anything else, connect its speaker to its audience. This is what Aristotle, the first Western authority on rhetoric, called ethos—the basic movement in any effective speech that transforms the “me” of the speaker and the “you” of the audience into “we”: “Friends, Romans, countrymen…”
Ethos is established by, quite literally, speaking the audience’s language: shared jokes, common reference points, recognisable situations. As the rhetorical theorist Kenneth Burke has said: “You persuade a man only in so far as you can talk his language by speech, gesture, tonality, order, image, attitude, idea, identifying your ways with his.” You can then take the shared language—and with it your audience—wherever you want it to go.