My dad’s love of foreign languages began when he gave up bus conducting and crossed the English Channel to fight Francisco Franco and become a Communist. In Catalonia, a fighter told him that if the International Brigades had known Esperanto, they might have had more success. When someone at a Communist Party school called Esperanto petty bourgeois — then the Moscow line — he was shocked and disappointed. He told me later, “He’s wrong; it’s a good idea. It’s communism in words. One day, everyone will speak it.”

In the early twentieth century, many other revolutionaries embraced this language, seeing it as a tool to build international solidarity. Esperanto faded, along with many of those hopes, as it faced decades of attacks from fascist and communist states alike. But amid a rising tide of nationalism, its legacy is worth preserving.