Various ancient Greek cities occasionally had laws against poetry, drama, and music. Because of its power to affect people's emotions and attitudes, and by extension opinions, they felt it was dangerous and labeled it black magic, witchcraft, whatever the ancient Greek word for bad juju is. I don't suppose they were far from the mark. A really good protest song or otherwise political piece of music will at the very least cause me to reevaluate my hard-won moderate-ness.