Eratosthenes of Cyrene (c. 276-195 BC) was an ancient Greek polymath who became chief librarian at Alexandria's legendary library. Born in Cyrene (modern Libya), he studied in Athens before being summoned to Alexandria by Ptolemy III. Though critics nicknamed him "Beta" for always placing second in every field, his colleagues called him "Pentathlos" for his well-rounded expertise in mathematics, geography, astronomy, poetry, and music theory. His final years brought blindness, and rather than li