For hundreds of years, Euclid's geometry disappeared with the fall of the Roman Empire. But in Constantinople, Islamic mathematicians, including Al-Khwarizmi (who gave us the word "algebra") worked long and hard on proving the Fifth Postulate. Support us on Patreon! http://bit.ly/EHPatreon (--More below) Subscribe for new episodes every week! http://bit.ly/SubToEC Grab your Extra Credits gear at the store! http://bit.ly/ExtraStore Thanks for participating in this week's discussion! We want you to be aware of our community posting guidelines so that we can have high-quality conversations: https://goo.gl/HkzwQh Contribute community subtitles to Extra Credits: http://www.youtube.com/timedtext_cs_panel?c=UCCODtTcd5M1JavPCOr_Uydg&tab=2 Talk to us on Twitter (@ExtraCreditz): http://bit.ly/ECTweet Follow us on Facebook: http://bit.ly/ECFBPage Get our list of recommended games on Steam: http://bit.ly/ECCurator ___________ Would you like James to speak at your school or organization? For info, contact us at: contact@extra-credits.net ____________ ♪ Get the intro music here! http://bit.ly/1EQA5N7 *Music by Demetori: http://bit.ly/1AaJG4H ♪ Get the outro music here! http://bit.ly/23isQfx *Music by Sean and Dean Kiner: http://bit.ly/1WdBhnm