The Stoics were the followers of the school of stoicism, founded in Athens by Zeno of Citium. Stoics were especially popular in Rome, characterized by the famous philosophers Seneca and Epictetus, as well as the emperor Marcus Aurelius.
Stoics believed that ethical behavior was the thrust of human existence and that self-control could overcome destructive emotions. Only when one controlled behavior and achieved clear thinking could one discover logos, or the universal reason. The Stoics also developed propositional logic, which defines an argument as a set of propositions.
Stoics believed that all being was corporeal, and that knowledge can be acquired through reason. The senses are receiving sensations, which the mind can then judge, distinguishing falsehood from reality. Stoics characterized the universe as consisting of active and passive substances. Matter is a passive substance, while Logos is the active substance.
The term stoic has come to mean indifferent to pain or unemotional, because Stoics taught that reason could triumph over passions. Wisdom was self-control and one strove to be free of passions, which in the ancient world had more of a connotation of “suffering” than emotions. Stoics believed that this was a way of life more than just a philosophy, and the Meditations of Marcus Aurelius present numerous stoic practices. Stoics also held the notion that all human beings were equal.