Answer:
Thesis Statement
Martin Luther King used metaphors in his "I Have A Dream" speech to try to help his audience understand his points.
Example 1
One extended metaphor that he used was about banking, saying that everyone attending the March on Washington had come to "cash a check."
Example 2
Because seasons and the sequence of yearly seasons were familiar to people, Martin Luther King was able to relate the long, hot days of summer when tempers were hot too, being followed by the cooler times of fall when many systems like schools went back into session for a new year.
Concluding Statement
By relating his ideas to things his listeners were familiar with, Martin Luther King helped his listeners really hear what he had to say. The implication is that when someone makes a promise, they should pay what they owe, whether that was literally cash or rights and justice. That check had been made out to all 'men' in the Declaration of Independence, promising everyone "Life, Liberty, and the Pursuit of Happiness." This "promissory note" had come back marked as "insufficient funds" for black men across America's history.