" Our inclination to act well towards others, whatever its source, tends to be confined to those with whom we share a common identity. The Greeks, the world’s first philosophers and scientists, regarded anyone who was not Greek as a barbarian – a word derived from the sound of a sheep bleating. Our radius of moral concern has limits. The group may be small or large, but in practice as opposed to theory, we tend to see those not like us as less than fully human. "

― Jonathan Sacks , Not in God's Name: Confronting Religious Violence