What did the ancient Stoics actually teach?

The ancient Stoics taught that a good, flourishing life depends on virtue and on nothing else. Virtue meant the perfected condition of human reason, and living virtuously meant living in agreement with nature, both one's own and that of the whole cosmos. Things most people chase, such as wealth, health and reputation, were judged neither good nor bad. Stoicism was also a complete system of physics, logic and ethics, not only a set of tips for calm. [1] [2]

From Zeno onward, Stoic philosophy had three parts: physics, logic and ethics. Logic covered more than formal reasoning; it also took in topics now sorted into philosophy of language, epistemology and philosophy of mind. The Stoics held that the three parts work together as a coherent whole, though scholars dispute how strongly that claim of systematization should be read. The orthodox position was that mastering all three is required for human flourishing, even though the overall goal is ethical. A commentary in The Conversation notes that much of this technical structure is missed by modern social-media presentations of Stoicism. [1] [3]

Stoic ethics aims at happiness (eudaimonia), a view shared with rival schools such as the Epicureans and Peripatetics. The schools differed over what happiness consists in. According to the Stanford Encyclopedia, Zeno described the end as living in agreement, meaning with one concordant reason and free of inner conflict. His successor Cleanthes added the phrase with nature. [1]

The longer formula reflects Stoic physics. The universe is pervaded by a rational active principle, identified with God or Zeus, which shapes matter according to a perfectly rational plan. To live in agreement with nature is to bring one's own reason into line with that of the whole. [1] [4]

The Stoics argued that virtue is all that is needed for happiness. They treated the virtues, including prudence, justice, courage and moderation, as forms of knowledge, and held that whoever has one has them all. Because knowledge is all-or-nothing, so is virtue. The Stanford entry notes a scholarly disagreement over how far this knowledge extends into logic and physics, with some interpreters, such as Annas, offering an alternative view. [1] [5]

Life, health, pleasure, beauty, wealth and reputation, and their opposites, were called indifferents. The argument was not that wealth sometimes harms and sometimes helps. It was that what is good necessarily benefits, as what is hot necessarily heats, and wealth neither benefits nor harms in itself. Two of the Stoics' most contentious claims follow: happiness is fully in our power, and virtue is the only good. [1]

The Internet Encyclopedia of Philosophy describes Stoic ethics as aiming to remove destructive passions, while still allowing appropriate emotional responses grounded in rational understanding. It also stresses fulfilling personal, social, professional and civic roles. The results here say little about the details of Stoic psychology, so this account is brief on that point. [6]