How does the author use foreshadowing in I Have a Dream: Writings and Speeches That Changed the World?

Examples of foreshadowing from the text:

“I am happy to join with you today in what will go down in history as the greatest demonstration for freedom in the history of our nation.”

In using quotations from Lincoln's address, King foreshadows his own message.

Five score years ago, a great American, in whose symbolic shadow we stand signed the Emancipation Proclamation. This momentous decree came as a great beacon light of hope to millions of Negro slaves who had been seared in the flames of withering injustice. It came as a joyous daybreak to end the long night of captivity.