Who was Zeno of Citium, the founder of Stoicism?

Zeno of Citium (c. 334-262 BC) founded the Stoic school around 300 BC in Athens, but he arrived at philosophy by accident. Diogenes Laertius records that Zeno, a merchant from Citium on Cyprus, was shipwrecked off the coast of Piraeus while carrying a cargo of purple dye; having lost his goods, he wandered into Athens and picked up a copy of Xenophon's Memorabilia in a bookseller's shop. Struck by its account of Socrates, he asked the bookseller where he could find men like that, and was pointed toward Crates the Cynic, who became his first teacher. Zeno later summed up the wreck itself in a line Diogenes Laertius preserves: "I made a prosperous voyage when I suffered shipwreck." After studying under teachers associated with the Cynic, Megarian, and Academic schools, Zeno began teaching on his own around 300 BC at the Stoa Poikile ("Painted Porch"), a public colonnade in the Athenian agora decorated with murals of historical and mythological battle scenes - the location gave the new school its name, since Zeno's followers came to be called Stoikoi, "men of the Stoa." Zeno taught that living well means living in agreement with nature and reason, that virtue alone is sufficient for happiness, and that emotions like fear, grief, and uncontrolled desire arise from mistaken judgments about what is genuinely good or bad - positions that remained the core of Stoic ethics for the next five centuries. He led the school for roughly three decades before his death and was succeeded as its second head by Cleanthes, whose Hymn to Zeus is the earliest complete Stoic text to survive; Chrysippus, the school's third head, later systematized Zeno and Cleanthes's teaching into the logically rigorous form that let Stoicism compete with the Academy and the Lyceum. The far better-known Roman Stoics - Seneca, Epictetus, Marcus Aurelius - all trace their school's lineage back to this one shipwrecked merchant's chance encounter with a bookseller.