Duties are universally measured by relations. Is a certain man your father? In this are implied taking care of him, submitting to him in all things, patiently receiving his reproaches, his correction. But he is a bad father. Is your natural tie, then, to a good father? No, but to a father. Is a brother unjust? Well, preserve your own just relation toward him. Consider not what he does, but what you are to do to keep your own will in a state conformable to nature, for another cannot hurt you unless you please. You will then be hurt when you consent to be hurt. In this manner, therefore, if you accustom yourself to contemplate the relations of neighbor, citizen, commander, you can deduce from each the corresponding duties.