This quote has a literal and figurative meaning. Literally, if a nation has citizens who are starving or impoverished, they will look for someone to blame. When no one comes to their rescue (such as in Germany during their depression), they will rise up themselves or follow someone who directs their anger toward a target (again in Germany, Hitler used the Germans' anger over WWI's aftermath and their economic depression to kindle anger and hatred for the Jews).
Figuratively, if someone is hungry for power, attention, etc., he or she often becomes angry toward whoever or whatever prevents that person from obtaining power or attention. Shakespeare uses this idea when his Caesar says that he "likes not [Cassius's] lean and hungry look"; he would prefer to be surrounded by fat men. He knows that Cassius wishes him ill will and that "fat men" are satisfied men. They have no reason to be angry toward their government, leader, or country.