Here's a quote I really love... "Real courtesy is this; each one has such humility as to consider everyone else better than himself, so that instead of the superior being condescending to the inferior, instead of the inferior eliminating the superior. Rather, you do have this relationship in which the inferior is served by the superior and considers him better than himself. Why consider anyone else better than ourselves? Well, first of all we can be absolutely sure about the worst in ourselves. We know that. But we can never be sure about the worst that is in our neighbor, we can only suspect that. Now since we can be sure about how rotten we are, we certainly ought to be polite to those people we can't even be so sure about."