On this day in 1887, L. L. Zamenhof published his first book introducing what would later become known as Esperanto. In it he proposed a “universal vote,” in which people would pledge to learn the International Language as soon as ten million people had signed the pledge. In an early indicator of the rapid worldwide success that would characterize Esperanto, within the first two years almost a thousand people had signed the pledge. If the number ever reaches ten million, those people will be morally obliged to learn Esperanto. Today, as Wikipedia points out, “Esperanto is the working language of several non-profit international organizations such as the Sennacieca Asocio Tutmonda, a left-wing cultural association which had 724 members in over 85 countries in 2006”—a figure that amounts, on average, to more than eight and a half per country.