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.

Five score years ago, a great American, in whose symbolic shadow we stand today, 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 their captivity. (1.1 – 2.1)

Was MLK right about the March on Washington being the greatest demonstration of all time? It's hard to measure these things, but at least 200,000 people were in attendance. The entire Washington mall was blanketed by people and picket signs. In short, this was one of the biggest deals in the history of big deals.

But these opening lines are really all about the man on the penny—Honest Abe Lincoln. The speech took place in front of the Lincoln Memorial, making the guy who ended slavery a literal backdrop for the event. MLK even told his allies that he wanted the speech to sound like Lincoln's Gettysburg Address.

There's a specific point of all the references to Lincoln, and it's not just about name-dropping. By bringing up the "captivity" of slavery, MLK is making the case that discrimination, segregation, and racism were a new kind of captivity—subtler than the outright atrocity of racism, but still outrageous.