Stoicism (Greek Στωικισμός) is a school of Hellenistic philosophy founded in Athens by Zeno of Citium in the early 3rd century BC. The Stoics taught that destructive emotions resulted from errors in judgment, and that a sage, or person of "moral and intellectual perfection", would not suffer such emotions.
Stoics were concerned with the active relationship between cosmic determinism and human freedom, and the belief that it is virtuous to maintain a will (called prohairesis) that is in accord with nature. Because of this, the Stoics presented their philosophy as a way of life, and they thought that the best indication of an individual's philosophy was not what a person said but how he behaved.
Later Stoics, such as Seneca and Epictetus, emphasized that because "virtue is sufficient for happiness", a sage was immune to misfortune. This belief is similar to the meaning of the phrase "stoic calm", though the phrase does not include the "radical ethical" Stoic views that only a sage can be considered truly free, and that all moral corruptions are equally vicious.
From its founding, Stoic doctrine was popular with a following throughout Greece and the Roman Empire, including the Emperor Marcus Aurelius, until the closing of all philosophy schools in 529 AD by order of the Emperor Justinian I, who perceived their pagan character as being at odds with the Christian faith.
Read more about Stoicism: Basic Tenets, History, Stoic Physics and Cosmology, Stoic Ethics and Virtues, Social Philosophy, Stoicism and Christianity, Modern Usage, Stoic Quotations, Stoic Philosophers