Stoicism is a school of Hellenistic philosophy that flourished throughout the Roman and Greek world until the 3rd century AD. Stoicism is predominantly a philosophy of personal ethics which is informed by its system of logic and its views on the natural world. According to its teachings, as social beings, the path to happiness for humans is found in accepting this moment as it presents itself, by not allowing ourselves to be controlled by our desire for pleasure or our fear of pain, by using our minds to understand the world around us and to do our part in nature's plan, and by working together and treating others in a fair and just manner.
It was founded in Athens by Zeno of Citium in the early 3rd century BC. The Stoics taught that emotions resulted in errors of judgment which were destructive, due to 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 religion (lex divina), and they thought that the best indication of an individual's philosophy was not what a person said but how a person behaved. To live a good life, one had to understand the rules of the natural order since they taught that everything was rooted in nature.
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 during the Roman Empire—and its adherents included the Emperor Marcus Aurelius. It later experienced a decline after Christianity became the state religion in the 4th century AD. Over the centuries, it has seen revivals, notably in the Renaissance (Neostoicism) and in the modern era (modern Stoicism).