Why the heck is “America” called “America” and not, say, “Columbia?” You’ll find the answer to that question and many more in Toby Lester‘s fascinating and terrifically readable new book The Fourth Part of the World: The Race to the Ends of the Earth, and the Epic Story of the Map That Gave America its Name (Free Press, 2009). As Toby points out, medieval Europeans thought the earth had three parts–Europe, Asia and Africa, with Jerusalem at the dead center and water all around. (And no, they didn’t think the earth was flat…). But in 1507 a peculiar item appeared–the Waldseemuller map— that outlined a fourth part of the world called “America,” with the Atlantic Ocean on the one side and an unnamed ocean on the other. Here’s the really curious thing though: at that time no European had ever seen what we now call the “Pacific Ocean.” Balboa was the first to see it, and he didn’t do so until 1513. So where did Waldseemuller and his colleagues get the idea that there was a continent between Europe and Asia and that an undiscovered ocean separated Asia from it? Was it just a good (educated) guess, or did the mapmakers have information that has not come down to us? You want the answer? Well you can listen to the interview and then go buy the book. All will be reveled!Please become a fan of “New Books in History” on Facebook if you haven’t already. Learn more about your ad choices. Visit megaphone.fm/adchoices