Duties are universally measured by relations. Is anyone a father? If so, it is implied that the children should take care of him, submit to him in everything, patiently listen to his reproaches, his correction. But he is a bad father. Are you naturally entitled, then, to a good father? No, only to a father. Is a brother unjust? Well, keep your own situation towards him. Consider not what he does, but what you are to do to keep your own faculty of choice in a state conformable to nature. For another will not hurt you unless you please. You will then be hurt when you think you are hurt. In this manner, therefore, you will find, from the idea of a neighbor, a citizen, a general, the corresponding duties if you accustom yourself to contemplate the several relations.