What did Lincoln mean in the Gettysburg Address?

The address was brief — fewer than three hundred words — and I confess I was not certain at the time that I had done the occasion justice. Yet the ideas in it were ones I had been turning over for years. Let me take the argument in order. I began by reaching back to the founding. As I said in a speech at Chicago some years before Gettysburg, the Declaration of Independence contains an electric cord — the proposition that all men are created equal — that links "the hearts of patriotic and liberty-loving men together." The nation was not merely a legal arrangement. It was a moral claim, and the war was a test of whether any nation built on that claim could survive. Then came the heart of it. The soldiers had already settled the question of what that ground meant. As I said in the Address itself, “The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract”. My words and the ceremony were secondary things. The real charge fell upon the living. The dead had done their part. It remained for us to finish the work — to ensure, as I closed the Address, “this nation under God shall have a new birth of freedom, and that government of the people, by the people, for the people shall not perish from the earth”. In short: the war was a test of democratic self-government itself, and the fallen had purchased our chance to pass that test.