Epictetus

Epictetus (c. 50–135 AD) was a Greek Stoic philosopher born into slavery in Hierapolis, Phrygia (modern Turkey). Freed after the death of Nero, he studied under the Stoic teacher Musonius Rufus and went on to found his own school in Nicopolis. His teachings, preserved by his student Arrian in the Discourses and the Enchiridion (Handbook), form the practical foundation of Stoic ethics. His central teaching — that we must distinguish between what is in our power and what is not — has influenced thinkers from Marcus Aurelius to modern cognitive behavioral therapy.