The Enchiridion   

indeed, who can speak like him?), have a mind to be philosophers too.
Consider first, man, what the matter is, and what your own nature
is able to bear. If you would be a wrestler, consider your shoulders,
your back, your thighs; for different persons are made for different
things. Do you think that you can act as you do, and be a philosopher?
That you can eat and drink, and be angry and discontented as you are
now? You must watch, you must labor, you must get the better of certain
appetites, must quit your acquaintance, be despised by your servant,
be laughed at by those you meet; come off worse than others in everything,
in magistracies, in honors, in courts of judicature. When you have
considered all these things round, approach, if you please; if, by
parting with them, you have a mind to purchase apathy, freedom, and
tranquillity. If not, don't come here; don't, like children, be one
while a philosopher, then a publican, then an orator, and then one
of Caesar's officers. These things are not consistent. You must be
one man, either good or bad. You must cultivate either your own ruling
faculty or externals, and apply yourself either to things within or
without you; that is, be either a philosopher, or one of the vulgar.
30. 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. Is 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.
31. Be assured that the essential property of piety towards the gods
is to form right opinions concerning them, as existing "I and as governing
the universe with goodness and justice. And fix yourself in this resolution,
to obey them, and yield to them, and willingly follow them in all
events, as produced by the most perfect understanding. For thus you
will never find fault with the gods, nor accuse them as neglecting
you. And it is not possible for this to be effected any other way
than by withdrawing yourself from things not in our own control, and
placing good or evil in those only which are. For if you suppose any
of the things not in our own control to be either good or evil, when
you are disappointed of what you wish, or incur what you would avoid,
you must necessarily find fault with and blame the authors. For every
animal is naturally formed to fly and abhor things that appear hurtful,
and the causes of them; and to pursue and admire those which appear
beneficial, and the causes of them. It is impractical, then, that
one who supposes himself to be hurt should be happy about the person
who, he thinks, hurts him, just as it is impossible to be happy about
the hurt itself. Hence, also, a father is reviled by a son, when he
does not impart to him the things which he takes to be good; and the
supposing empire to be a good made Polynices and Eteocles mutually