# Tweet by [@keefmoon](http://twitter.com/keefmoon) on 2019-09-30 19:39:29 > [!INFO] Archived from [original tweet](http://twitter.com/keefmoon/status/1178756268045066245) RT @noornet: This still gives me chills. Ingenious. Carl Sagan explains how the Ancient Greeks, Eratosthenes of Cyrene, the chief libraria…