Eratosthenes of Cyrene (c. 276 BC – c. 194 BC) was a Greek mathematician, geographer, poet, astronomer, and music theorist. He was a man of learning, becoming the chief librarian at the Library of Alexandria. He invented the discipline of geography, including the terminology used today. He is best known for being the first person to calculate the circumference of the Earth, which he did by applying a measuring system using stadia, a standard unit of measure during that time period. His calculation was remarkably accurate. He was described by the Suda Lexicon as Pentathlos which can be translated as "All-Rounder", for he was skilled in a variety of things, a true polymath.
