Today, L.L. would make his pitch for an international language by video on Kickstarter or Indiegogo. In the 19th century, he published this booklet which explains his motivation, the rules and key vocabulary to his new language and is also a marketing campaign to make people sign a pledge to learn the language if 10 million others do so too. According to Wikipedia, there are about 2 million people speaking Esperanto at some level of competence with 2000 native speakers with some really frenezaj gepatroj.

It is interesting to look at Zamenhof's implicit assumptions. While he speaks about the common man's ability to learn the language (which is essentially true), the text is clearly directed towards highly educated people who know German, French and Latin, so that they easily recognize the roots of a word like "proksimo" - Latin proximus. A person speaking only German would be at a complete loss to understand it, as would a French person faced with sxuldo (Schuld) - debt. Zamenhof hoped to attract the elite to his language which would then trigger the rest to learn his language too.

As with Klingon, Elvish and Dothraki, learning artificial languages remains a minority hobby, thankfully now supported by a Duolingo app (Klingon, though, still a work in progress). ( )