A passage from Epictetus
Epictetus, Discourses 1.16.20
✱
If I were a nightingale, I would do what is proper to a nightingale, and if I were a swan, what is proper to a swan.
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.
✱
At dawn, when you have trouble getting out of bed, tell yourself: 'I have to go to work — as a human being.'