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.