Have you seen the Amistad? I can think of few more heart rending movies. It tells the story of a group of Africans captured and sold into slavery who break free on board ship and kill almost all of the crew. They are captured and taken to Massachusetts, where they stand trial for murdering the crew.
Their case makes it all the way to the supreme court, where John Quincy Adams helps defend them with a stirring speech. In it, he raises the point that we think about too little.
He argues that the case hinges on the fundamental question, What is man? More specifically, he asks, are men by nature free or are they by nature slaves?
This story is deeply disturbing but among the very few important movies. Watch it.