Ataraxia
Formulated by Epicurus (-306)
Definition
Ataraxia (from the Greek ataraxia, 'unperturbedness') is a state of robust tranquility and freedom from mental disturbance that several rival schools of Hellenistic philosophy treated as the highest good. For Epicurus, it is reached by dispelling false beliefs, chiefly the fear of the gods and of death, and by limiting desire to what is natural and necessary. Pyrrhonist skeptics arrived at the same calm by suspending judgment on all non-evident matters, while the Stoics pursued a closely related state through aligning judgment with reason. Across all three schools, the shared premise is that disturbance stems from unexamined opinion rather than from external events themselves, so the untroubled mind is achieved by correcting belief, not by changing circumstances.