Stoicism is a philosophy holding that virtue is the only genuine good, that everything else is indifferent, and that a life lived in accordance with reason and nature is sufficient for flourishing.

The school

Zeno of Citium founded it in Athens around 300 BC, teaching at the painted porch — the stoa — from which the name comes. The Roman period produced the texts that survive most fully: Seneca's letters, the discourses of Epictetus, and the private notebooks of Marcus Aurelius.

The central division

Epictetus opens the Enchiridion with the distinction the whole system rests on. Some things are up to us — judgment, impulse, desire, aversion — and some are not: body, reputation, office, the actions of others. Suffering comes from treating the second group as though it belonged to the first.

The discipline follows. Direct effort at what you control, accept what you do not, and treat external outcomes as material for the exercise of virtue rather than as the point of the exercise. Apatheia is the result: freedom from destructive passion, which the Stoics distinguished from indifference to other people.

Physics and fate

The ethics rests on a physics. The cosmos is a rational, ordered whole pervaded by logos, and events follow necessarily. Accepting that order willingly is amor fati in its later form — Nietzsche took the phrase and changed its footing.

Because reason is shared by all people, the Stoics argued that everyone belongs to a single community, which made them early defenders of cosmopolitanism and influenced later theories of natural law.

The modern reading

Contemporary popular Stoicism takes the control dichotomy and the practical exercises while leaving the physics behind. That is a real loss of coherence: the ancient argument for accepting fate depends on the claim that the order is rational. What survives intact is the observation that most distress comes from judgments about events rather than from the events themselves.