The other Platonic figure was Eratosthenes the geographer, a sometime Academy student who came to Alexandria and became director of the Great Library around 267. His nickname in the ancient world was Pentathlos, the all-around scholar-athlete. Indeed, his writings show an impressively wide range of interests, from geometry, astronomy, and mathematics (including a work on the philosophy of mathematics that he called, strikingly, the Platonicus) to history, metaphysics, and poetry. Using his observations of the different shadows cast by sundials along the same meridian and a little number
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