If you wish your children and your wife and your friends to live forever,
you are foolish, for you wish things to be in your power which are not
so, and what belongs to others to be your own. So likewise, if you wish
your servant to be without fault, you are foolish, for you wish vice not
to be vice but something else. But if you wish not to be disappointed in
your desires, that is in your own power. Exercise, therefore, what is in
your power. A man’s master is he who is able to confer or remove whatever
that man seeks or shuns. Whoever then would be free, let him wish
nothing, let him decline nothing, which depends on others; else he must
necessarily be a slave.