Greek polymath most noted for his calculation of the circumference of the earth and his invention of the discipline of geography, was born in Cyrene in modern Libya, an outpost of Greek culture; he was exposed early to exotic contacts at the end of the Greek world. Nothing is known about his youth, but by the 260s BCE he was studying in Athens, primarily with the founder of Stoicism, Zeno of Citium, and Arcesilaus of Pitane, the director of the Academy. He was also a close associate of the mathematician Archimedes, who dedicated at least one work to him. Eratosthenes was thus trained in the wide variety of thought that Hellenistic Athens offered, and his early writings demonstrate his ability in philosophy, philology, and mathematics. But there are few details about the nearly twenty years that he spent in the city.
In 246 BCE the new Ptolemaic king Ptolemy III ...