Ataraxia
Ataraxia is a state of freedom from mental disturbance, often translated as 'tranquility' or 'imperturbability.' Several Hellenistic schools, including the Stoics, the Epicureans, and the Skeptics, treated it as a central goal, though they disagreed sharply about how to reach it. For the Stoics, ataraxia follows from accepting what is outside your control and focusing your effort only on your own judgments and actions.
Why it matters
It explains what Stoic practice actually aims at: not the absence of feeling, but freedom from being disturbed by things outside your control.
Where it comes up
Read about Ataraxia on Wikipedia
