To reduce man to the duties of his own city, and to disengage him from duties to the members of other cities, is to break the universal society of the human race.
Six mistakes mankind keeps making century after century: Believing that personal gain is made by crushing others; Worrying about things that cannot be changed or corrected; Insisting that a thing is impossible because we cannot accomplish it; Refusing to set aside trivial preferences; Neglecting development and refinement of the mind; Attempting to compel others to believe and live as we do.