L.L. Zamenhof was a Jewish eye doctor born in 1859 in Bialystok, a city split among Russians, Poles, Germans, and Jews who could not speak to one another. He concluded that language barriers were the root of the hostility he saw and spent years engineering a neutral, regular language that anyone could learn quickly. This episode traces the design of Esperanto, published in 1887 under the pseudonym Doktoro Esperanto, meaning one who hopes.

We look at why the earlier constructed language Volapuk failed, how Esperanto builds words from roots and fixed affixes, the ten-million-signature pledge that drew about a thousand replies, the first World Congress in 1905, and Zamenhof's decision to hand the language to an independent academy. Then we follow the darker chapters: condemnation in Mein Kampf, Gestapo raids, Stalin's purges of Esperantists, a ...