Zeno of Citium, a Cypriot merchant shipwrecked in Athens around 312 BCE, wandered into a bookshop, read Xenophon's Memorabilia of Socrates, and asked where one might find such men. The bookseller pointed at the passing philosopher Crates the Cynic. Zeno followed, and by about 301 BCE was teaching his own philosophy under the Stoa Poikile — the Painted Porch — on the north side of the Athenian Agora. The school named itself after the building. The tradition is now read mostly through the Roman Stoa: Seneca (Nero's tutor, ordered to suicide), Epictetus (born a slave, leaving the Enchiridion via his student Arrian), and Marcus Aurelius (whose Meditations was personal notebooks from the Danube frontier).
The Stoic system rests on a small number of structurally connected commitments. The dichotomy of control — the opening of Epictetus's Enchiridion — distinguishes what is up to us (judgments, impulses, desires) from what is not (body, reputation, possessions, others' actions, external events). Wisdom places concern only in what is up to us; suffering arises from misallocating concern to what we cannot control. Virtue (arete) is the only good; all else — health, wealth, reputation, life itself — is an indifferent, some preferred and others dispreferred. The four cardinal virtues (practical wisdom, justice, courage, temperance) come in unity-of-the-virtues form. Apatheia is freedom from destructive passions: the Stoic does not feel less than others but feels correctly. The practical program is exercises — morning preview, evening review, premeditation of evils (rehearse possible misfortunes so they cannot ambush), view from above (life seen from cosmological distance), memento mori — meant to reshape moral character over time. Christianization absorbed substantial Stoic vocabulary; the tradition went underground through the medieval period and was revived in Renaissance humanism, particularly by Justus Lipsius whose De Constantia (1584) launched Neostoicism. The modern psychological reception runs through Albert Ellis's Rational Emotive Behavior Therapy (1955), which cited the Enchiridion as its theoretical foundation; Beck's CBT descends from REBT, making Stoic technique the most clinically validated philosophical tradition in current use.
The Modern Stoicism movement, organized around Stoic Week and Stoicon since 2012, is one of the largest contemporary practical-philosophy revivals. Ryan Holiday's The Obstacle Is the Way (2014) and The Daily Stoic (2016) have collectively sold several million copies and routinely appear on business-leadership reading lists. Military adoption has its iconic instance: Vice Admiral James Stockdale, the senior US POW in the Hanoi Hilton for over seven years, attributed his survival to having studied the Enchiridion before deployment — the Stockdale Paradox (face the brutal facts but never lose faith) became a Jim Collins leadership lesson in Good to Great. Critics include Martha Nussbaum (the tradition's downgrading of emotion is a deep theoretical mistake) and political critics (Stoic acceptance can underwrite quietism). The Stoic-Buddhist convergence (brief 291) is the most-noted contemporary cross-current.