A passage from Epictetus
Epictetus, Discourses 3.2.1
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There are three topics in which the man who would be wise and good must be exercised: that which concerns desires and aversions, that which concerns pursuits and avoidances, and thirdly, the topic of freedom from deception.
Related passages
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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.
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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.
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At dawn, when you have trouble getting out of bed, tell yourself: 'I have to go to work — as a human being.'