" Cultures that have social classes, those that have caste systems, and those that practice slavery, all show significantly more of both shame and violence than cultures whose institutions do not divide people in those hierarchical ways. The existence of inequality exposes everyone to the risk of being inferior, which in turn stimulates aggressive competition to inflict the inferior status on others (such as by enslaving, impoverishing, or degrading them). In other words, inequality stimulates shame and shame stimulates the creation of inequality; shame stimulates violence and violence stimulates shame; inequality leads to violence and violence leads to inequality. These are all mutually reinforcing "vicious circles", or positive feedback loops. "

― James Gilligan , Preventing Violence