Stoicism 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 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 that 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.