Many Stoics—such as Seneca and Epictetus —emphasized that because "virtue is sufficient for happiness ", a sage would be emotionally resilient to misfortune. This belief is similar to the meaning of the phrase "stoic calm", though the phrase does not include the traditional Stoic view that only a sage can be considered truly free and that all moral corruptions are equally vicious.^[3]

The Stoics are especially known for teaching that "virtue is the only good" for human beings, and those external things—such as health, wealth, and pleasure—are not good nor bad in themselves (adiaphora ) but have value as "material for virtue to act upon." Alongside Aristotelian ethics , the Stoic tradition forms one of the major founding approaches to virtue ethics .^[1] The Stoics also held that certain destructive emotions resulted from errors of judgment, and they believed people should aim to maintain a will (called prohairesis ) that is "in accordance with nature ".

The word "stoic" commonly refers to someone who is indifferent to pain, pleasure, grief, or joy.^[8] The modern usage as a "person who represses feelings or endures patiently" was first cited in 1579 as a noun and in 1596 as an adjective .^[9] In contrast to the term "Epicurean ", the Stanford Encyclopedia of Philosophy ' s entry on Stoicism notes, "the sense of the English adjective 'stoical' is not utterly misleading with regard to its philosophical origins".^[10]