How the Declaration of Independence evolved

They are words etched into America's conscience-- And these are timeless qualities-- life, liberty, pursuit of happiness.

--foundational principles preserved in this rare draft of the Declaration of Independence, written by Thomas Jefferson, now on display at the Library of Congress. Ryan Reft is a lead curator. This is Jefferson's fully realized draft. You can see them changing words throughout.

The document contains edits from fellow Founding Fathers Ben Franklin and John Adams, like using the word "citizens" instead of "subjects." They were breaking from a monarchy and creating a country based on this creedal idea established in the declaration, that that was new and that we were not subject to anyone.

And there were other changes, according to historian Kevin Butterfield. Initially, Thomas Jefferson had said, "We hold these rights to be sacred and undeniable." And then Franklin said, no, actually, maybe we should say "self-evident."

But it was the phrase that "all men are created equal" that took time to evolve. Initially, the "all men are created equal" probably only apply to white men. It ignored women, enslaved folks, Native Americans and others. But that's the great thing about the Declaration. Even in its weaknesses, there is strength, the sense that the language he created enabled those folks who were unequal at the time to judge for themselves what equality was.

The exhibit, called The Declaration's Promise,showcases that evolution through other items, like President Abraham Lincoln's draft of the Gettysburg Address during the Civil War. He says, why are we here? Why did we fight this war? And he comes down to one basic idea-- equality.

The collection also features a declaration of rights read by Susan B. Anthony in support of women's suffrage to speeches by Dr. Martin Luther King, Jr. and John Lewis during the civil rights movement. These are moments to look back and see where we are and see where we should be.

And to see where we could be in the next 250 years. Nikole Killion, CBS News,Washington. The building blocks of this great country. Nikole, thank you.