A passage from Epictetus
Epictetus, Discourses IV.6
✱
He who is not master of his passions is not free. He is dragged about by desire and fear, and is the slave of fortune.
Related passages
✱
Men seek retreats for themselves, houses in the country, sea-shores, and mountains... But this is altogether a mark of the most common sort of men, for it is in thy power whenever thou shalt choose to retire into thyself.
✱
Take away thy opinion, and then there is taken away the complaint, 'I have been harmed.' Take away the complaint, and the harm is taken away.
✱
If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment.