"We the people, in order to form a more perfect union." Two hundred and twenty one years ago, in a hall that still stands across the street, a group of men gathered and, with these simple words, launched America's improbable experiment in democracy. Farmers and scholars; statesmen and patriots who had traveled across an ocean to escape tyranny and persecution finally made real their declaration of independence at a Philadelphia convention that lasted through the spring of 1787. The document they produced was eventually signed but ultimately unfinished. It was stained by this nation's original sin of slavery, a question that divided the colonies and brought the convention to a stalemate until the founders chose to allow the slave trade to continue for at least twenty more years, and to leave any final resolution to future generations.