It is worthwhile for one to make an effort to achieve happiness. Just as the purpose of a plant is to grow, so it is that the main purpose of every human being is to survive and to grow until death.
So we must lay it down that the association which is a state exists not for the purpose of living together but for the sake of noble actions. Those who contribute most to this kind of association are for that very reason entitled to a larger share in the state than those who, though they may be equal or even superior in free birth and in family, are inferior in the virtue that belongs to a citizen. Similarly they are entitled to a larger share than those who are superior in riches but inferior in virtue.