Massimo Pigliucci in Aeon:
The year is 133 BCE. The place Rome. Tiberius Gracchus, a tribune of the plebes, is killed in the streets, together with 300 of his supporters. He had angered many in the Senate by sponsoring anti-aristocratic legislation, in particular redistribution of land, a shortened military service, and broadened access to the privileges afforded by Roman citizenship. It is a well-known episode in the history of ancient Rome.
What is less known is that Tiberius had been advised all along by a Stoic philosopher, Gaius Blossius, one of many examples of Stoics deeply involved with politics and social reforms. Gaius had worked for years with Tiberius to improve the condition of the common people. When he saw his friend slaughtered, he left Rome and decided that the time to play by the rules had passed. Plutarch tells us that Blossius moved to the province of Asia (modern western Turkey), where he joined a rebellion against Rome led by Eumenes III, a pretender to the throne of Pergamon. The revolt was initially successful. Eumenes was able to seize a number of cities in Anatolia, conquer the island of Samos (where both Pythagoras and Epicurus had been born), and kill the Roman consul, Publius Licinius Crassus. However, the Roman Senate eventually dispatched another consul, the experienced Marcus Perperna, to the region, and he was able to extinguish the revolt. When the upraising failed, Blossius committed suicide, in typical Stoic fashion.
Stoicism has seen a surprising revival in recent years, and has become a popular philosophy of life, a kind of Western response to Buddhism (with which it has much in common). However, it remains the subject of a number of criticisms, some more justified than others. Despite multiple episodes like the one featuring Blossius, modern critics of Stoicism claim that the philosophy is self-involved and lacks resources to meaningfully engage at the political level.