There’s an old Yiddish joke about an Esperanto convention where participants were given license to “crocodile” — speak their native languages — during a break in the proceedings. After a long day of speaking Esperanto, listening to speeches in Esperanto, singing songs and reading signs in Esperanto, they were relieved to be able to stop reaching for words. As they streamed out of the hall, one Esperantist after the other turned to his or her fellows and exclaimed with a sigh, “A mekhaye shoyn, redn a yidish vort” — “It’s such a pleasure to be able to speak Yiddish already.”

It’s an exaggeration, to be sure. Esperantujo, the unlocalizable community of Esperanto speakers, has never been particularly Jewish, but as Esther Schor points out at welcome length in “Bridge of Words: Esperanto and the Dream of a Universal Language,” Esperanto arose in response to Jewish concerns. Although Ludovik Zamenhof, the language’s sole begetter, developed a plan for a lingvo internacia while still a teenager, it took him until the ripe age of 28 to revise and refine it enough for public consumption. His “Unua Libro” (“First Book”), which introduced Esperanto to the world, was published in 1887 — roughly nine years after Zamenhof devised a plan for the renovation and standardization of Yiddish, a project with which he continued to tinker for at least 30 more years. Though Schor never says so in so many words, she makes it clear that Esperanto, in its origins at any rate, was intended as Yiddish for everybody; Yiddish, that is, for goyim. But where Yiddish is the national language of nowhere, Esperanto was meant to be the alternate language of everywhere, a universal second language, “neutral, nonethnic and nonimperial,” that would “commit its users to transcend nationalism.”

Zamenhof’s hope that “All translations would be made into it alone, as into a tongue intelligible to all” anchors the language even more deeply in Yiddish, which served for a thousand years as taytsh, the language into which students at every level of the Central and East European Jewish school system translated and explained the biblical and rabbinical texts that they were studying. There is a direct line from the kheyder, the traditional Jewish elementary school, to a language that Schor characterizes as “invented not to transcend translation but to transact it.”

But there’s more to it than Yiddish. Schor’s account of Zamenhof’s dreams and disappointments, including the religious ideas that he — and he alone — saw as essential to Esperanto’s mission, turns into an increasingly anecdotal survey of the language and its culture in the century since Zamenhof’s death. Although Esperantists refer to themselves as samideanoj (from the English “same idea”), Esperantujo seems never to have lacked for either colorful characters or the “dirtiness of fighting” that George Orwell, whose aunt Nellie was one of those characters, ascribed to the so-called international languages: Schor looks at Marxist Esperantists, Stalinist Esperantists, Nazi Esperantists and anti-traditional Far Eastern Esperantists, along with the samideanoj she encounters in her travels. Author of a biography of Emma Lazarus, Schor is less assured as a memoirist than as a scholar, and while these latter sections are not without some interest, they go on at greater length than the material warrants. This is, however, a minor quibble. In portraying a language condemned by both Hitler and Stalin, then used by the American military as the language of the pseudo-Communist “Aggressor” in a lengthy series of Cold War maneuvers, “Bridge of Words” leaves us in no doubt that whatever Esperanto might be doing, it seems to be doing it right.