Saluton! Ĉu vi parolas Esperanton? Chances are you don’t—speak Esperanto, that is. But a few readers of the last two columns—about the quandary of Europe’s multilingualism, and why enforcing English throughout Europe was a flawed idea—made the case for Esperanto. At a time when ever more countries need to communicate with one another, why shouldn’t Europe, or the world, embrace the simple international language invented by Ludwig Zamenhof in 1887?

Outsiders tend to scoff at Esperanto as an idealistic waste of time. Esperantists harrumph back: with somewhere between a few hundred thousand and possibly 2m learners, Esperanto is far and away world’s most successful invented language. If that sounds like “Finland’s biggest klezmer band”, it shouldn’t. Esperanto has outgrown quite a few rivals. Dreamers have been inventing languages for centuries, from Lojban (designed around predicate logic) to Ladaan (designed to espouse feminism). But languages like Klingon, Elvish, Dothraki, Navi’i and their kin, created for popular entertainment, are the only invented languages that can muster nearly the enthusiasm Esperanto does.

Esperanto remains atop the heap. The Esperanto Wikipedia has nearly 186,000 articles, more than Hindi or Hebrew, and some 87,000 users, far and away the most among invented languages. Esperanto-speakers gather offline in frequent conventions too, discussing the language’s prospects, making friends and falling in love. An Esperantists’ apartment-share service, Pasporta Servo, boasts over a thousand homes in 90 countries where Esperantists can stay with each other for free. The community’s cheery energy is depicted by Arika Okrent in her book “In the Land of Invented Languages". Esperantists’ pride is not totally without foundation.

One element behind Esperanto’s success is obviously its simplicity. Zamenhof designed it to spread. Roots come from the main European languages. Grammar is utterly regular. (Nouns end in –o, adjectives in –a, adverbs in –e. Plurals get a –j, and so on.) And Esperantists are keen to teach: sign up at Lernu and you will find not only free, decent-quality lessons but free tutoring from experienced speakers. There are few actual “native” speakers, perhaps around a thousand. Many have heard Esperanto since birth by idealistic parents, but Ms Okrent describes just one, Kim Henriksen, who speaks Esperanto as his dominant language.

With all this said—and having been warned by Ms Okrent that "there is nothing worse than being on the receiving end of an Esperanto proselytiser"—Johnson must confess his doubts. Esperanto will probably never become the world’s lingua franca. Why not? Well, one reason is simple: It hasn’t yet, in almost 130 years. Esperanto isn’t quite as old as The Economist, but it’s older than, say, Norway or Stanford University. Yet it remains thin on the ground.

This is partly because language, more than any other tool, benefits from network effects. The more people who speak a language, the more desirable that language will be. This is of course why Esperanto speakers play up the biggest possible numbers for their community—the hopes that others will join, for the benefit of being able to use Esperanto with more people.

But beyond sheer numbers, people learn a language in order to enjoy a living and real human culture. This holds Esperanto back. Google “famous Esperanto speakers” and you will find Wikipedia’s list. Many names are not exactly famous. But one jumps out: J.R.R. Tolkien. The novelist (and language inventor) apparently briefly dabbled in Esperanto. But he later wrote to a reader that

Volapük, Esperanto, Ido, Novial, &c &c are dead, far deader than ancient unused languages, because their authors never invented any Esperanto legends. [From letter 180.]

For “legends”, we might read more broadly “culture”. People may learn English or German or Chinese to get a job. But they also learn languages to experience travel, food, film, music and literature. Look at the cover of a language textbook and you’ll find an attractive person strolling down a stereotypically picturesque street from the country in question, or maybe a famous landmark. “That,” thinks the learner, “is what I want.”

What would that picture be for an Esperanto textbook? The community is proud of its respect for existing cultures. Esperanto is to be the world's first choice for a second language in order to protect diversity, not to replace it. So to be motivated to learn Esperanto, you have to be motivated not by a living and breathing culture, but by an ideal of international harmony. That ideal has to compete with French food, Italian fashion, Brazilian music, Spanish nightlife, American rock'n’roll, Japanese film, and so on.

Perhaps if a few gorgeous celebrities became fluent in Esperanto and required it for admission to their parties, Esperanto would pick up some cultural cachet. It would certainly be interesting if a country or territory ever made a serious effort to make Esperanto its language, as a tiny sliver of Belgium once nearly did. Until that (distant) day, living languages will reign supreme—and especially the living language that has lucked into Esperanto's desired role as the world’s most popular auxiliary: English. Those who cherish language diversity might prefer Johnson's previous suggestion of "English plus". This seems a better bet than the noble dream of Esperanto, which has never become reality, and probably never will.