Discourses, On Anxiety (solicitude)

Epictetus — The Slave

Are we anxious about forming false beliefs? No, because that's up to us. Are we anxious about acting against our nature? No, not even that. When you see someone turn pale, a doctor looks at their complexion and says, "This person's spleen is sick" or "That person's liver is sick." You should do the same thing. Say, "This person's desires are sick. Their fears are sick. They're not thinking straight. They have a fever." Nothing else makes someone change color, shake, chatter their teeth, or drop to their knees and pace around.

Epictetus — The Slave Original

Are we anxious about not forming a false opinion? No, for this is in my power. About not exerting our movements contrary to nature? No, not even about this. When then you see a man pale, as the physician says, judging from the complexion, this man's spleen is disordered, that man's liver; so also say, this man's desire and aversion are disordered, he is not in the right way, he is in a fever. For nothing else changes the color, or causes trembling or chattering of the teeth, or causes a man to Sink in his knees and shift from foot to foot.