Zeitgeist: Moving Forward really got me hooked with the first part, discussing human behavior and nature vs. nurture. Can violence be on our dna?
Better than the first two, I would definitely recommend it.
"In a decaying society, art, if it's truthful, must also reflect decay. And unless it wants to break faith with its social function, art must show the world as changeable. And help to change it." - Ernst Fischer